#include using namespace std; int main() { long long n; cin >> n; assert(1 <= n && n <= 200000); vector a(n); for (int i = 0; i < n; ++i) { int p; cin >> p; assert(0 <= p && p < n); assert(!a[p]); a[p] = 1; } for (bool&& i: a) assert(i); }