#include using namespace std; using ll=long long; #define rep2(i, a, n) for(int i = (a); i < (n); i++) #define rep(i, n) rep2(i,0,n) int main(){ cin.tie(nullptr);ios_base::sync_with_stdio(false); string s;cin>>s; map map; rep(i,s.size())map[s[i]]++; char target; for(auto itr=map.begin();itr!=map.end();++itr){ //cout<<"key="<first<<",val="<second<<"\n"; if(itr->second==1){ target=itr->first; break; } } rep(i,s.size()){ if(target==s[i]){ cout<