package cn.itcast.girl.TheBlueCup_02;
import java.util.Scanner;
public class JourneyToTheWest {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
String str1 = sc.nextLine();
String str2 = sc.nextLine();
int n = sc.nextInt();
String a[] = str1.split(":");
String c[] = str2.split(":");
String b[] = new String[3];
String d[] = new String[3];
for(int i=0;i<a.length;i++) {
b[i] = a[i];
}
for(int i=0;i<3;i++) {
if(b[i]=="") {
b[i]="0";
}
}
for(int i=0;i<c.length;i++) {
d[i] = c[i];
}
for(int i=0;i<3;i++) {
if(d[i]=="") {
d[i]="0";
}
}
int hour,minute,second;
hour = Integer.parseInt(d[0])-Integer.parseInt(b[0]);
minute = Integer.parseInt(d[1])-Integer.parseInt(b[1]);
second = Integer.parseInt(d[2])-Integer.parseInt(b[2]);
long sum = 0;
sum = (long)(hour*3600 + minute*60 + second)*n;
System.out.println(sum);
sc.close();
// int c[] = new int;
// for(int i=0;i<3;i++) {
// c[i] = Integer.parseInt(b[i]);
// }
// System.out.println(a.length);
}
}