#include <iostream> #include <unordered_map> using namespace std; int main() { string s; cin >> s; unordered_map<char, int> char_count; for (char c : s) { char_count[c]++; } for (char c : s) { if (char_count[c] == 1) { cout << c << endl; return 0; } } cout << "no" << endl; return 0; }