#include<bits/stdc++.h>
using namespace std;
int res[30];
int main()
{
string s;
cin >> s;
int len = s.size();
for (int i = 0; i < len; i ++) {
res[s[i] - 'a'] ++;
}
for (int i = 0; i < len; i ++) {
if (res[s[i] - 'a'] == 1) {
cout << s[i] << endl;
return 0;
}
}
cout << "no" << endl;
return 0;
}
求关注