include [HTML_REMOVED]
using namespace std;
char str[100010];
int cnt[26];
int main() {
cin >> str;
int len = strlen(str);
for(int i = 0;i < len;i ){
cnt[str[i] - ‘a’] ;
}
for(int i = 0; i < len ;i ++){
if(cnt[str[i] - ‘a’] ==1){
cout << str[i] <<endl;
return 0;
}
}
puts(“no”);
return 0;
}