#include<iostream>
using namespace std;
int main()
{
	string a,b;
	getline(cin,a);
	getline(cin,b);
	long long n;
	scanf("%lld",&n);
	long long suma=0;
	long long sumb=0;
	long long k=0;
	long long ac=0;
	while(a[k]!=':')
	{
		ac*=10;
		ac+=a[k]-'0';
		k++;
	}
	suma+=ac*3600;
	k++; 
	ac=0;
	while(a[k]!=':')
	{
		ac*=10;
		ac+=a[k]-'0';
		k++;
	}k++; 
	suma+=ac*60;
	ac=0;
	while(k!=a.size())
	{
		ac*=10;
		ac+=a[k]-'0';
		k++;
	}k++; 
	suma+=ac;
	k=0;
	ac=0;
	while(b[k]!=':')
	{
		ac*=10;
		ac+=b[k]-'0';
		k++;
	}k++; 
	sumb+=ac*3600;
	ac=0;
	while(b[k]!=':')
	{
		ac*=10;
		ac+=b[k]-'0';
		k++;
	}k++; 
	sumb+=ac*60;
	ac=0;
	while(k!=b.size())
	{
		ac*=10;
		ac+=b[k]-'0';
		k++;
	}k++; 
	sumb+=ac;
	printf("%lld",(sumb-suma)*n);
	return 0;
	
 }