#include <bits/stdc++.h> using namespace std; int main() { long long int h1,h2,m1,m2,s1,s2; int t; long long s; char c; cin>>h1>>c>>m1>>c>>s1; cin>>h2>>c>>m2>>c>>s2; cin>>t; s1=h1*3600+m1*60+s1; s2=h2*3600+m2*60+s2; s=t*(s2-s1); cout<<s<<endl; return 0; }