#include<stdio.h>
int main()
{
	int a,b,c,d,e,f,n;
	scanf("%d:%d:%d",&a,&b,&c);
	scanf("%d:%d:%d",&d,&e,&f);
	scanf("%d",&n);
	unsigned long sum;
	sum=(d*3600+e*60+f-a*3600-b*60-c)*n;
	printf("%lu",sum);
	return 0;
}