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