Primar

#include <fstream>
#include <algorithm>
#define x first
#define y second
#define M 1000000007
using namespace std;
pair<int,int> p[5001];
int n,i,j,h,w,mini,maxi,mi,ma;
int vs[5001][5001], vd[5001][5001];
long long suma;

int main()
{
    ifstream cin("primar.in");
    ofstream cout("primar.out");
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    for(i = 1; i <= n; i++)
        cin >> p[i].x >> p[i].y;
    sort(p+1, p+n+1);

    for(i = 1; i <= n; i++){
        maxi = 0;
        mini = M;
        mi = 0; ma = 0;
        for(j = i+1; j <= n; j++){
            if((p[j].y < mini)and(p[j].y > p[i].y)){
                mini = p[j].y;
                mi = j;
            }
            if((p[j].y > maxi)and(p[j].y < p[i].y)){
                maxi = p[j].y;
                ma = j;
            }
            if((mini < M)and(maxi > 0))
            {
                vs[mi][ma] = i;
                vs[ma][mi] = i;
            }

        }
    }
    for(i = n; i >= 1; i--){
        maxi = 0;
        mini = M;
        mi = 0; ma = 0;
        for(j = i-1; j >= 1; j--){
            if((p[j].y < mini)and(p[j].y > p[i].y)){
                mini = p[j].y;
                mi = j;
            }
            if((p[j].y > maxi)and(p[j].y < p[i].y)){
                maxi = p[j].y;
                ma = j;
            }
            if((mini < M)and(maxi > 0))
            {
                vd[mi][ma] = i;
                vd[ma][mi] = i;
            }

        }
    }
    suma = 0;
    for(i = 1; i < n; i++)
        for(j = i+1; j <= n; j++)
            if(vs[i][j] and vd[i][j]){
                if(p[i].y > p[j].y) h = p[i].y - p[j].y - 1;
                else h = p[j].y - p[i].y - 1;
                w = p[vd[i][j]].x - p[vs[i][j]].x - 1;
                suma += 1LL * h * w;
            }
    cout << suma % M << endl;
    return 0;
}