//2024.7.25
//by white_ice
//#8776. Not Another Constructive!
#include <bits/stdc++.h>
#define itn int
#define isN (st[i]=='N')
#define isA (st[i]=='A')
#define isC (st[i]=='C')
#define EM (st[i]=='?')
using namespace std;
constexpr int oo=45;
constexpr itn op=2505;

bitset <op> f[oo][oo][oo];
char ans[oo];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);

	string st;
	int n,m;
	cin >> n >> m >> st;
	st=' '+st;
	for (int i=0;i<=n;i++)
        f[0][0][i][0]=1;
	for (int i=1;i<=n;i++){
		for (int j=0;j<=i;j++){
			for (int k=0;k<=n-i;k++){
				if (!isN && !isA && !isC)
                    f[i][j][k] |= f[i-1][j][k];
				if ((isN||EM) && j)
                    f[i][j][k] |= f[i-1][j-1][k];
				if (isA||EM)
                    f[i][j][k] |= (f[i-1][j][k]<<(j*k));
				if (isC||EM)
                    f[i][j][k] |= f[i-1][j][k+1];
			}
		}
	}
	int res=-1;
	for (int i=0;i<=n;i++)
        if (f[n][i][0][m]) 
            res=i;

	if (res == -1){
		cout << "-1\n";
		return 0;
	}

    int j = res,k=0,l=m;
	for (int i=n;i>=1;i--){
		if (isN||(EM && j && f[i-1][j-1][k][l]))
            ans[i]='N',j--;
		else if (isA||(EM && j*k<=l&&f[i-1][j][k][l-j*k])) 
            ans[i]='A',l -= j*k;
		else if (isC||(EM && f[i-1][j][k+1][l])) 
            ans[i]='C',k++;
		else ans[i]=st[i];
	}
	for (int i=1;i<=n;i++)
        cout << ans[i];
	return 0;
}