#include <iostream>
 
using namespace std;
 
int k, n;
 
string a[100];
string f[100];
 
int main(){
	cin >> n >> k;
	for (int i = 1; i <= n-k+1; i++){
		cin >> a[i]; 
	}
	for (int i = 1; i <= 26; i++){
		f[i]="A";
		f[i+26]="B";
	}
	for (int i = 1; i <= 26; i++){
		f[i]+=(char)i+96;
		f[i+26]+=(char)i+96;
	}
	for (int i = 1; i <= n-k+1; i++){
		if (a[i]=="NO"){
			f[i+k-1] = f[i];
		}
	}
	for (int i = 1; i <= n; i++){
		cout << f[i] << " ";
	}
	return 0;
}

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

OSA4CllFUyBOTw==

9 8
YES NO