CSP drawing

#include<bits/stdc++.h>

using namespace std;

const int N = 1000;

int a[N][N];

int main() {
    
	int n;
	scanf("%d", &n);
	for (int i = 0; i <= 110; i++) {
    
		for (int j = 0; j <= 110; j++) {
    
			a[i][j] = 0;
		}
	}
	for (int i = 0; i < n; i++) {
    
		int x1, y1, x2, y2;
		scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
		int minx=min(x1,x2);
		int maxx=max(x1,x2);
		int miny=min(y1,y2);
		int maxy=max(y1,y2);
		for (int j = minx+1; j <= maxx; j++) {
    
			for (int k = miny+1; k <= maxy; k++) {
    
				a[j][k] = 1;
			}
		}
	}
	int sum=0;
	for(int i=0;i<=110;i++) {
    
		for(int j=0;j<=110;j++) {
    
			if(a[i][j]) sum++;
			//printf("%d ",a[i][j]);
		}
		//printf("\n");
	}
printf("%d\n",sum);
	return 0;
}