#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <vector>
#include <cstring>
#include <algorithm>
#include <math.h>

using namespace std;

void perest(long p[10]);

long p[10];
char b[10];
long m;

int main()
{
   freopen("input.txt","r", stdin);
   freopen("output.txt", "w",stdout);
   int n,j;
   cin>>n>>m;
   for (int i=1; i<=n; i++)
        b[i] = 'A' + i - 1;
   for (int i = 0; i<=m; i++)
    p[i] = i;
   do
   {
       perest(p);
       j = m;
       while (j>0 && p[j] == j+n-m){
        cout<<p[j];
        j--;
       }
       cout<<endl;
       if (j>0)
       {
        p[j]++;
        for (int i=j+1; i<=m; i++)
        p[i] = p[i-1] + 1;
       }
   }
   while (j>0);
return 0;
}

void perest(long p[10])
{
    long x,l,r,j,k;
    while (p[0] == 0)
    {
        for (int i=1; i<=m; i++)
            cout<<b[p[i]];
        cout<<endl;
        j = m;
        while (p[j]<p[j-1])
            j--;
        k = m;
        while (p[k]<p[j-1])
            k--;
        x = p[k];
        p[k] = p[j-1];
        p[j-1] = x;
        l = j;
        r = m;
        while (l < r)
        {
            x = p[l];
            p[l] = p[r];
            p[r] = x;
            l++;
            r--;
        }
    }
}