#308 (div.2) A. Vanya and Table

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<algorithm>
#include<string>
#include<sstream>
#include<set>
#include<vector>
#include<stack>
#include<map>
#include<queue>
#include<deque>
#include<cstdlib>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<ctime>
#include<functional>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;

#define me(s) memset(s,0,sizeof(s))
#define For(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define sz size
#define clr clear
#define F(a,b) for(int i=a;b;i++)

const int N=110;
int a

;
int main()
{
int n;
while(~scanf("%d",&n))
{
me(a);
int x1,x2,y1,y2;
while(n--)
{
scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
for(int i=y1;i<=y2;i++)
for(int j=x1;j<=x2;j++)
a[i][j]++;
}
int ans=0;
for(int i=1;i<=100;i++)
for(int j=1;j<=100;j++)
ans+=a[i][j];
printf("%d\n",ans);
}
return 0;
}