#include <stdio.h>

int main(){
	int val = 0;
	scanf("%d",&val);
	
	int shour, sminute, fhour, fminute,sum;
	for(int i = 0;i < val;i ++){
		scanf("%d%d%d%d",&shour,&sminute,&fhour,&fminute);
		if(sminute == 0){
			sum += (24 - shour) * 60;
		}else{
			sum += (24 - shour + 1) * 60;
		}
		sum += (sminute + fminute + (fhour * 60));
	}
	printf("%d",sum);
}