poj2017简单题

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int n,i;
    while(scanf("%d",&n)!=EOF)
    {
        int temp=0,sum=0,s,t;
        if(n==-1)
            break;
        for(i=0;i<n;i++)
        {
            scanf("%d %d",&s,&t);
            sum += s*(t-temp);
            temp=t;
        }
        printf("%d miles
",sum);
    }
    return 0;
}