#include "bits/stdc++.h"
 
#define ll long long
#define pb push_back
#define ff first
#define ss second
 
#define yes cout << "YES\n"
#define no cout << "NO\n"
#define Case(i) cout << "Case " << int(i) << ": "
 
#define lop(n) for (int i = 0; i < n; i++)
#define lopj(n) for (int j = 0; j < n; j++)
 
#define all(x) x.begin(), x.end()
#define sortd(x) sort(x.rbegin(), x.rend())
#define bitcount(x) __builtin_popcount(x)
 
#define vin vector <int>
#define vll vector <ll>
#define pll pair <ll, ll>
#define pii pair <int, int>
#define vpll vector <pll>
 
#ifndef ONLINE_JUDGE
#define dbg(x) cout << #x << " = " << x << endl;
#define dbg2(x, y) cout << #x << " = " << x << "\t", dbg(y);
#define dbg3(x, y, z) cout << #x << " = " << x << "\t", dbg2(y, z);
#define ddbg(x) cout << #x << " = [ "; for(auto z : x) cout << z << ' '; cout << "]\n";
#else
#define dbg(x)
#define adbg(x)
#define dbg2(x, y)
#define dbg3(x, y, z)
#define ddbg(x)
#endif
 
#define sob template < typename T
#define sb2 template < typename T, typename TT
sob > void print(T x) {std::cout << x << '\n';}
sb2 > void print(T x, TT y) {std::cout << x << ' ' << y << '\n';}
sb2 > void print(std::pair <T, TT> x) {std::cout << x.ff << ' ' << x.ss << '\n';}
// sob > void print(std::vector <T> v) {for (auto z : v) std::cout << z << ' '; std::cout << '\n';}
sob > void print(T x[], int n) {for(int i = 0; i++ < n;) std::cout << *x++ << (i < n ? ' ':'\n');}
 
using namespace std;
 
int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
 
	int n, k;
	cin >> n >> k;
	lop(k) cout << (char) (i + 'A');
	lop(n-k) cout << 'A';
 
	return 0;
}