#include <iostream> #include <cstring> using namespace std; int main() { char str[100001]; int a[26] = {0}; cin >> str; int len = strlen(str); for (int i = 0; i < len; i++) { a[str[i] - 'a']++; } for (int i = 0; i < len; i++) { if (a[str[i] - 'a'] == 1) { cout << str[i]; return 0; } } cout << "no"; return 0; }