#include<stdio.h>
int main() {
	int d = 0;
	scanf("%d", &d);  //个数：d*2;
	int z = d*2;
	int arr[100] = { 0 };
	for (int i = 0; i < z; i++) {
		scanf("%d", &arr[i]);
	}
	int ret = 0;
	int s = 0;
	for (int i = 0; i < z; i += 2) {
		ret = arr[i] +arr[i + 1] - 8 + ret;
		s = s + ret;
	}
	printf("%d\n", s);
	return 0;
}