#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; constexpr int INF = 1001001001; constexpr int mod = 1000000007; // constexpr int mod = 998244353; template inline bool chmax(T& x, T y){ if(x < y){ x = y; return true; } return false; } template inline bool chmin(T& x, T y){ if(x > y){ x = y; return true; } return false; } int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); int N; cin >> N; vector X(N), Y(N); for(int i = 0; i < N; ++i) cin >> X[i] >> Y[i]; vector> ys(20001); for(int i = 0; i <= 20000; ++i){ ys[i].emplace(-100); ys[i].emplace(20100); } int ans = 0; for(int i = 0; i < N; ++i){ bool ok = true; for(int x = max(0, X[i] - 19); x <= min(20000, X[i] + 19); ++x){ int dx = X[i] - x; int lb = -100, ub = Y[i]; while(ub - lb > 1){ int mid = (lb + ub) / 2; int dy = abs(mid - Y[i]); if(dx * dx + dy * dy >= 100) lb = mid; else ub = mid; } int low = lb; lb = Y[i], ub = 20100; while(ub - lb > 1){ int mid = (lb + ub) / 2; int dy = abs(mid - Y[i]); if(dx * dx + dy * dy >= 100) ub = mid; else lb = mid; } int high = ub; if(*ys[x].lower_bound(low) < high){ ok = false; break; } } if(ok){ ys[X[i]].emplace(Y[i]); ans += 1; } } cout << ans << endl; return 0; }