#include <fstream>
using namespace std;
ifstream f("cifra.in");
ofstream g("cifra.out");
int str,len,c1,c2,s,b[101],c[101];
int main ()
{
        f>>str;
        int len=strlen(str);
        char c1='0';
        if(len>1) c1=str[len-2];
        char c2='0';
        if(len) c2=str[len-1];
        int s=(c1-'0')*7;
        if((c1-'0')%2) s+=b[c2-'0'];
        else s+=a[c2-'0'];
        s=s%10;
        g<<s<<'\n';

    return 0;
    }