#include<iostream> #include<string> using namespace std; int main() { string a; int letters[26] = {0},len,sum = 0; getline(cin,a); len = a.length(); for(int i = 0;i < len;i++){ letters[a[i] - 'a']++; } for(int i = 0;i < len;i++){ if(letters[a[i] - 'a'] == 1){ cout<<a[i]<<endl; return 0; } } cout<<"no"<<endl; return 0; }