#include<iostream>
#include<string>
#include<algorithm>
 
 
int main()
{
 
 
 
    std::vector<std::string> v{"5","4","6","E","1","7","E","E","3","2"};
    std::vector<std::string> r{"1","2","3","4","5","6","7","8","9"};
 
    std::sort(v.begin(), v.end());
 
    //remove all elements which are not numbers
    std::vector<std::string> v_numbers;
    std::set_intersection(v.begin(), v.end(), r.begin(), r.end()
                        , std::back_inserter(v_numbers));
 
    //find minimum element
    std::string result = *std::min_element(v_numbers.begin(), v_numbers.end());
    std::cout<<result<<std::endl;
}