Forest

#include <iostream>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <unordered_set>
#include <stdio.h>
#include <string.h>
#include <unordered_map>
#include <fstream>
#include <set>

#define MOD 1000000007;
#define ll long long
#define N 131072

using namespace std;

struct p{
    ll x,y;
};

ll quad(p a){ ///quadrance. thank you based wildberger!
    return a.x*a.x+a.y*a.y;
}

p puut[2000];

int main(){
    ll n;
    cin>>n;
    ll u_x, u_y;
    cin>>u_x>>u_y;

    for(int i=0; i<n; i++){
        ll x,y;
        cin>>x>>y;
        puut[i].x=x-u_x;
        puut[i].y=y-u_y;
    }

    int vast=0;
    for(int i=0; i<n; i++){
        bool nakyvissa=1;
        for(int j=0; j<n; j++)
            if(i!=j){
                if(puut[i].x==0&&puut[j].x==0)
                    if(puut[i].y*puut[j].y>=0)
                        if(quad(puut[j])<quad(puut[i]))
                            nakyvissa=0;

                if(puut[i].x!=0&&puut[j].x!=0)
                    if(puut[j].x*puut[i].y==puut[i].x*puut[j].y)
                        if(puut[i].x*puut[j].x>=0)
                            if(quad(puut[j])<quad(puut[i]))
                                nakyvissa=0;
            }

        if(nakyvissa)
            vast++;
    }

    cout<<vast<<endl;

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED