UVa 11677 Alarm Clock Solution

#include<stdio.h>
#include<math.h>
int main()
{
int h1,h2,m1,m2,h,m;
while(scanf("%d%d%d%d",&h1,&m1,&h2,&m2)==4)
{
if(h1==0 && m1==0 && h2==0 && m2==0) break;
else
{
h=h2-h1;
m=m2-m1;
if(m<0)
{
m=m+60;
h=h-1;
}
if(h<0)
h=h+24;
}
printf("%d\n",h*60+m);
}
return 0;
}