#include <iostream> #include <string> using namespace std; char LJY ( string& s, int k) { if (s.empty() || k <= 0) return '0'; char c = s[0]; int count = 1; for (int i = 1; i < s.length(); ++i) { if (s[i] == c) { count++; } else { if (count >= k) { return c; } c = s[i]; count = 1; } } if (count >= k) { return c; } return '0'; } int main() { int k; cin >> k; string s; cin >> s; char r= LJY(s, k); if (r != '0') { cout << r << endl; } else { cout << "No" << endl; } return 0; }