#include <bits/stdc++.h>
int main(){for(int j=0;j<100;++j){std::set<char>a;char c;for(c='0';c<='9';++c){a.insert(c);}c=getchar();while(c!='\n'){a.erase(c);c=getchar();}std::cout<<*a.begin()<<std::endl;}}