2359.cpp

这是哈尔滨工业大学acmOJ的源代码

/* This Code is Submitted by wywcgs for Problem 2359 on 2006-09-14 at 18:20:01 */
#include <cstdio>
#include <algorithm>
using namespace std;

typedef long long int64;

int main()
{
	int n, s;
	
	while(scanf("%d %d", &n, &s) != EOF) {
		int64 cost = 0, bc = 1 << 28;
		for(int i = 0; i < n; i++) {
			int v, uc; scanf("%d %d", &v, &uc);
			bc = min(bc+s, (int64)v);
			cost += bc*uc;
		}
		printf("%lld\n", cost);
	}
	
	return 0;
}