#include<iostream>
#include<cmath>
#include<vector>

int main(){
using namespace std;

std::vector<int>input;
char newSymbol;

cin.sync_with_stdio(false);
std::cin>>newSymbol;

while(newSymbol!=46)
{
    cin.sync_with_stdio(false);
    input.push_back(newSymbol);
    std::cin>>newSymbol;
}


int vecSize=input.size()/5;

std::vector<int>allDNA(vecSize);

int str=0;
int firstDigit;
int secondDigit;
int thirdDigit;
int fourthDigit;
int fifthDigit;

for(int i=0;i<vecSize;++i)
{
    if(input[str+4]>=97&&input[str+4]<=102)
    {
        firstDigit=(int)input[str+4]-87;
    }else
    {
        firstDigit=input[str+4]-48;
    }

    if(input[str+3]>=97&&input[str+3]<=102)
    {
        secondDigit=((int)input[str+3]-87)*16;
    }else
    {
        secondDigit=(input[str+3]-48)*16;
    }

    if(input[str+2]>=97&&input[str+2]<=102)
    {
        thirdDigit=((int)input[str+2]-87)*16*16;
    }else
    {
        thirdDigit=(input[str+2]-48)*16*16;
    }

    if(input[str+1]>=97&&input[str+1]<=102)
    {
        fourthDigit=((int)input[str+1]-87)*16*16*16;
    }else
    {
        fourthDigit=(input[str+1]-48)*16*16*16;
    }

    if(input[str]>=97&&input[str]<=102)
    {
        fifthDigit=((int)input[str]-87)*16*16*16*16;
    }else
    {
        fifthDigit=(input[str]-48)*16*16*16*16;
    }


    allDNA[i]=firstDigit+secondDigit+thirdDigit+fourthDigit+fifthDigit;
    str+=5;
}

int resultHex;
bool checker=false;

for(int i=0;i<allDNA.size();++i)
{
    for(int j=0;j<allDNA.size();++j)
    {

        if(allDNA[i]==allDNA[j]&&i!=j)
        {
            allDNA.erase(allDNA.begin()+j);
            j-=1;
            checker=true;

        }

    }

    if(checker==false)
    {
        break;
    }else
    {
        allDNA.erase(allDNA.begin()+i);
        i-=1;
    }
    checker=false;
}

resultHex=allDNA[0];

long long resultDecFive=((resultHex/16.00)-(resultHex/16))*16;
resultHex/=16;

long long resultDecFour=((resultHex/16.00)-(resultHex/16))*16;
resultHex/=16;

long long resultDecThree=((resultHex/16.00)-(resultHex/16))*16;
resultHex/=16;

long long  resultDecTwo=((resultHex/16.00)-(resultHex/16))*16;
resultHex/=16;

long long  resultDecOne=((resultHex/16.00)-(resultHex/16))*16;


cout.sync_with_stdio(false);

switch(resultDecOne)
{
case 10:
    cout<<"a";
    break;
case 11:
    cout<<"b";
    break;
case 12:
    cout<<"c";
    break;
case 13:
    cout<<"d";
    break;
case 14:
    cout<<"e";
    break;
case 15:
    cout<<"f";
    break;
default:
    cout<<resultDecOne;
}

switch(resultDecTwo)
{
case 10:
    cout<<"a";
    break;
case 11:
    cout<<"b";
    break;
case 12:
    cout<<"c";
    break;
case 13:
    cout<<"d";
    break;
case 14:
    cout<<"e";
    break;
case 15:
    cout<<"f";
    break;
default:
    cout<<resultDecTwo;
}

switch(resultDecThree)
{
case 10:
    cout<<"a";
    break;
case 11:
    cout<<"b";
    break;
case 12:
    cout<<"c";
    break;
case 13:
    cout<<"d";
    break;
case 14:
    cout<<"e";
    break;
case 15:
    cout<<"f";
    break;
default:
    cout<<resultDecThree;
}

switch(resultDecFour)
{
case 10:
    cout<<"a";
    break;
case 11:
    cout<<"b";
    break;
case 12:
    cout<<"c";
    break;
case 13:
    cout<<"d";
    break;
case 14:
    cout<<"e";
    break;
case 15:
    cout<<"f";
    break;
default:
    cout<<resultDecFour;
}

switch(resultDecFive)
{
case 10:
    cout<<"a";
    break;
case 11:
    cout<<"b";
    break;
case 12:
    cout<<"c";
    break;
case 13:
    cout<<"d";
    break;
case 14:
    cout<<"e";
    break;
case 15:
    cout<<"f";
    break;
default:
    cout<<resultDecFive;
}

return 0;
}