#include<iostream>
using namespace std;
int main()
{
	int a,b,c,s1=0,s2=0,s3=0;
	cin>>a;
	for(int i=0;i<a;i++)
	{
		cin>>b>>c;
		s3=s1+b+c-8;
		s2=s2+s3;
		s1=b+c;
	}
	cout<<s2;
	return 0;
}

求助