# include<iostream> # include<cstring> using namespace std; int main(){ string a,b; int a_len,b_len,s=0; cin>>a; a_len=a.size(); for(int i=0;i<a_len-1;i++){ s=1; for(int j=i+1;j<a_len;j++){ if(a[i]==a[j]){ s++; break; } } if(s==1){ cout<<a[i]; return 0; } } cout<<"no"; return 0; }