#include <bits/stdc++.h> using namespace std; typedef long long ll; #define REP(i, n) for(int(i)=0;(i)<(n);++(i)) #define FOR(i, f, t) for(int(i)=(f);(i)<(t);(++i)) const int MOD = int(1e9+9); bool f[22222][22222]; int c = 0; int main(){ int n; cin >> n; REP(i,n){ int xx,yy; cin >> xx >> yy; bool b = true; for(int y = -19; y <= 19; y++){ for(int x = -19; x <= 19; x++){ int mx = xx + x, my = yy + y; if(mx < 0 || mx > 20000 || my < 0 || my > 20000) continue; if(f[my][mx] && (mx-xx)*(mx-xx)+(my-yy)*(my-yy) < 400){ b = false; } } } if(b) f[yy][xx] = true, c++; } cout << c << endl; return 0; }