# include <bits/stdc++.h>
# define maxn 100100
# define rep(i, j, k) for(int i = j; i <= k; ++i)
# define per(i, j, k) for(int i = j; i >= k; --i)
using namespace std;

int n, m, ans;
int pre[45], nxt[45], que[45], nop[maxn];
int dp[41][41][41][2501];
string s;

inline int cub(int x) {int tmp = (x + 2) / 3; return tmp * tmp * tmp;}

void dfs(int i, int j, int k, int l) {
    if(i == 0) return;
    if(s[i] == 'N') dfs(i - 1, j - 1, k, l), cout << 'N';
    else if(s[i] == 'A') dfs(i - 1, j, k, l - j * k), cout << 'A';
    else if(s[i] == 'C') dfs(i - 1, j, k + 1, l), cout << 'C';
    else if(s[i] == '?')
        if(dp[i - 1][j][k][l]) dfs(i - 1, j, k, l), cout << 'B';
        else if(dp[i - 1][j - 1][k][l]) dfs(i - 1, j - 1, k, l), cout << 'N';
        else if(l >= j * k && dp[i - 1][j][k][l - j * k]) dfs(i - 1, j, k, l - j * k), cout << 'A';
        else dfs(i - 1, j, k + 1, l), cout << 'C';
    else dfs(i - 1, j, k, l), cout << s[i];
}

signed main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> n >> m >> s; s = ' ' + s;
    rep(i, 1, n) {
        pre[i] = pre[i - 1] + (s[i] == 'N');
        if(s[i] != 'N' && s[i] != 'A' && s[i] != 'C' && s[i] != '?') nop[i] = nop[i - 1] + 1;
        que[i] = que[i - 1] + (s[i] == '?');
    }
    per(i, n, 1) nxt[i] = nxt[i + 1] + (s[i] == 'C');
    // rep(i, 1, n) cout << pre[i] << ' '; cout << '\n';
    // rep(i, 1, n) cout << que[i] << ' '; cout << '\n';
    // rep(i, 1, n) cout << nxt[i] << ' '; cout << '\n';
    // cerr << "I love Furina forever\n";
    rep(i, 0, n) dp[0][0][i][0] = 1;
    rep(i, 1, n) {
        rep(j, pre[i], pre[i] + que[i]) {
            rep(k, nxt[i + 1], nxt[i + 1] + que[n] - que[i]) {
                rep(l, 0, m) {
                    if(s[i] == 'N') dp[i][j][k][l] = dp[i - 1][j - 1][k][l];
                    else if(s[i] == 'C') dp[i][j][k][l] = dp[i - 1][j][k + 1][l];
                    else if(s[i] == 'A' && l >= j * k) dp[i][j][k][l] = dp[i - 1][j][k][l - j * k];
                    else if(s[i] == '?') {
                        if(j > 0) dp[i][j][k][l] = dp[i - 1][j - 1][k][l];
                        if(l >= j * k) dp[i][j][k][l] = dp[i][j][k][l] || dp[i - 1][j][k][l - j * k];
                        dp[i][j][k][l] = dp[i][j][k][l] || dp[i - 1][j][k + 1][l];
                        dp[i][j][k][l] = dp[i][j][k][l] || dp[i - 1][j][k][l];
                        // dp[i][j][k][l] = dp[i - 1][j - 1][k][l] || dp[i - 1][j][k + 1][l] || dp[i - 1][j][k][l - j * k] || dp[i - 1][j][k][l];
                    }
                    else dp[i][j][k][l] = dp[i - 1][j][k][l];
                    // cerr << i << ' ' << j << ' ' << k << ' ' << l << ' ' << dp[i][j][k][l] << '\n';
                }
            }
        }
    }
    // cerr << "Genshin Impact\n";
    rep(i, 0, n) ans = ans || dp[n][i][0][m];
    // cerr << dp[2][0][0][m] << ' ' << dp[2][1][0][m] << ' ' << dp[2][2][0][m] << '\n';
    if(ans == 0) {cout << -1; return 0;}
    // return 0;
    rep(i, 0, n) if(dp[n][i][0][m]) {dfs(n, i, 0, m), cout << '\n'; break;}
    return 0;
}