#include<iostream>
using namespace std;

int main()
{
ios::sync_with_stdio(false);
int word[26]={10,11,12,13,14,15,16,17,34,18,19,20,21,22,35,23,24,25,26,27,28,29,32,30,31,33};
int total;
string s;
while(cin>>s){
total=0;
for(int i=8;i>=1;--i)
total+=(s[8-i]-48)*i;
for(int i=0;i<26;++i)
if((total+word[i]%10*9+(word[i]-word[i]%10)/10)%10==10-s[8]+48)
cout<<static_cast<char>(i+65);
cout<<"\n";
}
return 0;
}