Mobile Communications

Description:

Input:

The first line contains three integers n, p and m (1 ≤ n ≤ 100 000, 1 ≤ p ≤ 10⁹, 1 ≤ m ≤ 10⁹, n ≤ m) — the number of days Arkady will top up the account, the amount of the daily payment, and the number of days you should check.

The i-th of the following n lines contains two integers d_i and t_i (1 ≤ d_i ≤ m, 1 ≤ t_i ≤ 10⁹) — the index of the day when Arkady will make the i-th top up, and the amount he will deposit on this day. It is guaranteed that the indices of the days are distinct and are given in increasing order, i. e. d_i > d_i - 1 for all i from 2 to n.

Output:

Print the number of days from the 1-st to the m-th such that the account will have a negative amount on it after the daily payment.

Sample Input:

3 6 7
2 13
4 20
7 9

Sample Output:

3

Sample Input:

5 4 100
10 70
15 76
21 12
30 100
67 85

Sample Output:

26

Note:

In the first example the balance will change as following (remember, initially the balance is zero):

1. in the first day 6 rubles will be charged, the balance in the evening will be equal to  - 6;
2. in the second day Arkady will deposit 13 rubles, then 6 rubles will be charged, the balance in the evening will be equal to 1;
3. in the third day 6 rubles will be charged, the balance in the evening will be equal to  - 5;
4. in the fourth day Arkady will deposit 20 rubles, then 6 rubles will be charged, the balance in the evening will be equal to 9;
5. in the fifth day 6 rubles will be charged, the balance in the evening will be equal to 3;
6. in the sixth day 6 rubles will be charged, the balance in the evening will be equal to  - 3;
7. in the seventh day Arkady will deposit 9 rubles, then 6 rubles will be charged, the balance in the evening will be equal to 0.

Thus, in the end of the first, third and sixth days the balance will be negative in the end of the day.