#include <stdio.h>
int main()
{
	int hour1,minute1;
	int hour2,minute2;
	scanf("%d %d",&hour1,&minute1);
	scanf("%d %d",&hour2,&minute2);
	
	int ih=hour2-hour1;
	int im=minute2-minute1;
	
	if(im<0){
		im=60+im;
		ih--;
	}
	
	printf("ʱ%dʱ%d",ih,im);
	return 0;
}