code:
<span style="font-size:18px;">#include <iostream>
#include <fstream>
using namespace std;
int speed[11];
int hour[11];
int main()
{
fstream in("input.txt");
int n;
while (cin >> n&&n != -1)
{
int sum = 0;
speed[0] = 0;
hour[0] = 0;
for (int i = 1; i <= n; i++)
{
cin >> speed[i] >> hour[i];
}
for (int i = 1; i <= n; i++)
{
sum += (speed[i]*(hour[i] - hour[i - 1]));
}
cout << sum << " miles" << endl;
}
//system("pause");
return 0;
}
</span>