#include <bits/stdc++.h>
#define all(a) begin(a), end(a)
#define int long long
using namespace std;

char dp[41][41][401][2501];
string s;

bool allow(int idx, char c){
	char c2 = s[idx];
	if (c2 == '?') return true;
	if (c == 'N' || c == 'A' || c == 'C') {
		return c == c2;
	} else {
		return c2 != 'N' && c2 != 'A' && c2 != 'C';
	}
}

#define forn(i, j) for (int i = 0; i <= j; i++)
void solve() {
	int n, k; cin >> n >> k;
	dp[0][0][0][0] = 'X';
	cin >> s;
	int N = 0, A = 0, C = 0;
	for (int i = 0; i < n; i++) {
		forn(x, N) forn(y, A) forn(z, C) {
			if (!dp[i][x][y][z]) continue;
			if (allow(i, 'N')) {
				dp[i + 1][x + 1][y][z] = 'N';
				N = max(N, x + 1);
			}
			if (allow(i, 'A')) {
				dp[i + 1][x][y + x][z] = 'A';
				A = max(A, y + x);
			}
			if (allow(i, 'C') && z + y <= k) {
				dp[i + 1][x][y][z + y] = 'C';
				C = max(C, z + y);
			}
			if (allow(i, 'X')) {
				dp[i + 1][x][y][z] = s[i] == '?' ? 'X' : s[i];
			}
		}
	}
	forn(x, N) forn(y, A) {
		if (dp[n][x][y][k]) {
			int z = k;
			string ans;
			for (int i = n; i >= 1; i--) {
				ans.push_back(dp[i][x][y][z]);
				char c = ans.back();
				if (c == 'N') {
					x -= 1;
				} else if (c == 'A') {
					y -= x;
				} else if (c == 'C') {
					z -= y;
				}
			}
			reverse(all(ans));
			cout << ans << '\n';
			return;
		}
	}
	cout << -1 << '\n';
}

int32_t main(){
#ifndef LOCAL
	cin.tie(0)->sync_with_stdio(false);
#endif
	int t = 1;
	// cin >> t;
	while (t--) {
		solve();
	}
}