#include #include using namespace std; using namespace atcoder; using ll=int; using ld=long double; ld pie=3.141592653589793; ll inf=144494; ll mod=1000000007; int main(){ ll n; cin >>n; vectorx(n),y(n); for (ll i = 0; i < n; i++) { cin >> x[i]>> y[i]; } map,ll>memo; ll ans=0; for (ll i = 0; i < n; i++) { bool ok=true; for (ll j = x[i]-20; j <=x[i]+20; j++) { for (ll k = y[i]-20; k <=y[i]+20; k++) { ll z=(x[i]-j)*(x[i]-j)+(y[i]-k)*(y[i]-k); if (z<400) { if (memo[{j,k}]==1) { ok=false; break; } } } if (!ok) { break; } } if (ok) { memo[{x[i],y[i]}]=1; ans+=1; } } cout << ans << endl; }