UVA 11677 - Alarm Clock : Solution

#include <stdio.h>
int main()
{
    int h1,h2,m1,m2,start,end,ans;
    while (scanf("%d%d%d%d",&h1,&m1,&h2,&m2)==4)
    {
        if (h1==0 && m1==0 && h2==0 && m2==0) break;
        start=h1*60+m1;
        end=h2*60+m2;
        if (start>end) ans=1440-start+end;
        else ans=end-start;
        intf("%d\n",ans);
    }
    return 0;
}