/*

     水题：读懂题目就能做

 */

 #include <cstdio>

 #include <iostream>

 #include <algorithm>

 #include <cstring>

 #include <cmath>

 #include <vector>

 #include <string>

 #include <queue>

 #include <map>

 #include <set>

 using namespace std;

 const int MAXN = 1e2 + ;

 const int INF = 0x3f3f3f3f;

 int a[MAXN][MAXN];

 int main(void)      //Codeforces Round #308 (Div. 2) A. Vanya and Table

 {

     // freopen ("A.in", "r", stdin);

     int n;

     while (scanf ("%d", &n) == )

     {

         memset (a, , sizeof (a));

         int x1, y1, x2, 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 = ;

         for (int i=; i<=; ++i)

         {

             for (int j=; j<=; ++j)    ans += a[i][j];

         }

         printf ("%d\n", ans);

     }

     return ;

 }