// YukiCoderなら通る

#include <algorithm>
#include <cstdio>
#include <vector>

int N;
std::vector<std::vector<bool>> hasCircle;

int distance(int x1, int y1, int x2, int y2){
    int dx = x1-x2, dy = y1-y2;
    return dx * dx + dy * dy;
}

int main(){
    hasCircle.resize(20001);
    for(int i=0;i<=20000;i++){
        hasCircle[i].resize(20001);
    }
    
    scanf("%d", &N);

    int n = 0;
    for(int i=0;i<N;i++){
        int x, y;
        scanf("%d %d", &x, &y);

        bool flag = false;
        for(int j=-20;j<=20;j++){
            for(int k=-20;k<=20;k++){
                int x2 = x + k, y2 = y + j;
                if(x2 < 0 || x2 > 20000 || y2 < 0 || y2 > 20000){
                    continue;
                }
                if(!hasCircle[y2][x2]){continue;}
                if(distance(x, y, x2, y2) < 400){
                    flag = true;
                    break;
                }
            }
            if(flag){break;}
        }

        if(!flag){
            hasCircle[y][x] = true;
            n += 1;
        }
    }

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