以下是代码：

#include <iostream>
using namespace std;
int main(){
    int a, b, c, d, e, f, g;
    char m;
    cin >> a >> m >> b >> m >> c >> d >> m >> e >> m >> f >> g;
    cout << ((d*3600+e*60+f)-(a*3600+b*60+c))*g;
    return 0;
}