#include <stdio.h>

int main(int argc,char *argv[])
{
int c,c1,c2;
while((c1=getchar())!=EOF)
      {
      c2=getchar();
      c=(c1<='9' ? c1-'0' : c1-('A'-10))<<4;
      c+=c2<='9' ? c2-'0' : c2-('A'-10);
      putchar(c);
      }
}