编程题：AFei Loves Magic
### Descriprion
AFei is a trainee magician who likes to study various magical materials. Today, he came to the forest to find rare materials. He was so lucky that he found a piece of high-level magic stone. He knew that this stone always appeared in the pile, so there must be more nearby. Then he went deeper.
As expected, he found many magic stones. These stones were arranged in a row. Just as he was ready to pick up one, a magical circle was triggered. He was petrified and the stones began to move. As mentioned above, the stones were lined up. Now, some stones moved to one end of the line and the other stones moved to the other end. Stones would not change direction of movement unless they collided with other stones. Collision meant that two stones moved to the same position, and then the directions of the two stones would both change. Whether or not a collision occured, the speed was always $1 \; m/s$. Stone would disappear when it reached one of the ends.
AFei knew that the magical circle would disappear after $t$ seconds. It meant that after $t$ seconds, he could move and the stones would return to immobility. This also meant that AFei would get those stones. He wondered how many magic stones he could get in the end, including the first one he got when he came to the forest.
### Input Description
The first line contains three integers $n, L, t \;(0 \leq n \leq 1000000, 2 \leq L \leq 1000000000, 0 \leq t \leq1000000)$ − the number of stones on the line is $n$，the length of the line is $L$ meters from $0$ to $L$ (position $0$ and $L$ are the two ends), and the magic circle will disappear after $t$ seconds.
The following $n$ lines contain description of magic stones on the line. Each $i_{th}$ of these lines contains two space-separated integers $x[i]$ and $d[i] \; (0 \lt x[i] \lt L, d[i] \in \{ 1, 2 \})$, which stand for initial position and direction of motion($1$ means from $0$ to $L$, $2$ means from $L$ to $0$).
Input guarantees that there will not be two magic stones in one location.
If stone $A$ and stone $B$ are located at $4$ and $5$, respectively, and $A$'s direction is $1$, $B$'s direction is $2$. Then next second, the position of the two stones have not changed, but they have gone in the opposite direction.
### Output Description
Output a number indicating the amount of the magic stones that AFei will eventually be able
to obtain.
### Sample Input 1
in
0 10000 3
### Sample Output 1
out
1
### Sample Input 2
in
4 10 6
1 1
5 2
6 1
9 2
### Sample Output 2
out
3
### Hint
The stones are $A(1,1), B(5,2), C(6,1), D(9,2)$.
After $1$s, they become $A(2,1), B(4,2), C(7,1), D(8,2)$;
After $2$s, they become $A(3,2), B(3,1), C(7,2), D(8,1)$;
After $3$s, they become $A(2,2), B(4,1), C(6,2), D(9,1)$;
After $4$s, they become $A(1,2), B(5,2), C(5,1), D$ reach $L$ and disappears;
After $5$s, they become $A$ reach $0$ and disappears, $B(4, 2), C(6,1), D$ disappeared;
After $6$s, they become $A$ disappeared, $B(3, 2), C(7, 1), D$ disappeared. AFei finially gets the first one, $B$ and $C$.
答案：若无答案欢迎评论
AFei is a trainee magician who likes to study various magical materials. Today, he came to the forest to find rare materials. He was so lucky that he found a piece of high-level magic stone. He knew that this stone always appeared in the pile, so there must be more nearby. Then he went deeper.
As expected, he found many magic stones. These stones were arranged in a row. Just as he was ready to pick up one, a magical circle was triggered. He was petrified and the stones began to move. As mentioned above, the stones were lined up. Now, some stones moved to one end of the line and the other stones moved to the other end. Stones would not change direction of movement unless they collided with other stones. Collision meant that two stones moved to the same position, and then the directions of the two stones would both change. Whether or not a collision occured, the speed was always $1 \; m/s$. Stone would disappear when it reached one of the ends.
AFei knew that the magical circle would disappear after $t$ seconds. It meant that after $t$ seconds, he could move and the stones would return to immobility. This also meant that AFei would get those stones. He wondered how many magic stones he could get in the end, including the first one he got when he came to the forest.
### Input Description
The first line contains three integers $n, L, t \;(0 \leq n \leq 1000000, 2 \leq L \leq 1000000000, 0 \leq t \leq1000000)$ − the number of stones on the line is $n$，the length of the line is $L$ meters from $0$ to $L$ (position $0$ and $L$ are the two ends), and the magic circle will disappear after $t$ seconds.
The following $n$ lines contain description of magic stones on the line. Each $i_{th}$ of these lines contains two space-separated integers $x[i]$ and $d[i] \; (0 \lt x[i] \lt L, d[i] \in \{ 1, 2 \})$, which stand for initial position and direction of motion($1$ means from $0$ to $L$, $2$ means from $L$ to $0$).
Input guarantees that there will not be two magic stones in one location.
If stone $A$ and stone $B$ are located at $4$ and $5$, respectively, and $A$'s direction is $1$, $B$'s direction is $2$. Then next second, the position of the two stones have not changed, but they have gone in the opposite direction.
### Output Description
Output a number indicating the amount of the magic stones that AFei will eventually be able
to obtain.
### Sample Input 1
in
0 10000 3
### Sample Output 1
out
1
### Sample Input 2
in
4 10 6
1 1
5 2
6 1
9 2
### Sample Output 2
out
3
### Hint
The stones are $A(1,1), B(5,2), C(6,1), D(9,2)$.
After $1$s, they become $A(2,1), B(4,2), C(7,1), D(8,2)$;
After $2$s, they become $A(3,2), B(3,1), C(7,2), D(8,1)$;
After $3$s, they become $A(2,2), B(4,1), C(6,2), D(9,1)$;
After $4$s, they become $A(1,2), B(5,2), C(5,1), D$ reach $L$ and disappears;
After $5$s, they become $A$ reach $0$ and disappears, $B(4, 2), C(6,1), D$ disappeared;
After $6$s, they become $A$ disappeared, $B(3, 2), C(7, 1), D$ disappeared. AFei finially gets the first one, $B$ and $C$.
答案：若无答案欢迎评论
