#include <iostream>
using namespace std;
int h1, m1, s1;
int h2, m2, s2;
char x;
int ans;
int y; 
int main(){
	cin >> h1 >> x >> m1 >> x >> s1 >> h2 >> x >> m2 >> x >> s2 >> y;
	ans=((h2 - h1) * 3600 + (m2 - m1) * 60 + (s2 - s1)) * y;
	cout << ans << endl;
	return 0;
}

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