#include <iostream>
using namespace std;
int main()
{
int i, j, k, n;
const char data[] = "ABCDEF";
n = sizeof(data) / sizeof(data[0]) - 1;
for( i = 0; i < n; i++ )
for( j = 0; j < n; j++ )
for( k = 0; k < n; k++ )
cout<<data[i]<<data[j]<<data[k]<<endl;
cin.get();
return 0;
}