#include <cstdio>
#include <string>
using i32 = int;
constexpr i32 N = 40, K = 2500;
i32 n, k;
char str[N + 5];
bool f[N + 1][N + 1][N + 1][K + 1];
char ch[N + 1][N + 1][N + 1][K + 1];
void work(i32 i, i32 a, i32 c, i32 sum) noexcept {
	if (!i) return;
	switch (ch[i][a][c][sum]) {
	case 'N':
		work(i - 1, a - 1, c, sum);
		break;
	case 'A':
		work(i - 1, a, c, sum - a * c);
		break;
	case 'C':
		work(i - 1, a, c + 1, sum);
		break;
	default:
		work(i - 1, a, c, sum);
		break;
	}
	putchar(ch[i][a][c][sum]);
}
signed main(i32 argv, char *argc[]) noexcept {
	if (argv != 1) {
		freopen((argc[1] + std::string(".in")).c_str(), "r", stdin);
		freopen((argc[1] + std::string(".out")).c_str(), "w", stdout);
	}
	scanf("%d%d%s", &n, &k, str + 1);
	i32 apn = 0, apc = 0, ap_ = 0, pr_ = 0;
	for (i32 i = 1; i <= n; ++i) apc += str[i] == 'C', ap_ += str[i] == '?';
	for (i32 i = 0; i <= ap_; ++i) f[0][0][apc + i][0] = true;
	for (i32 i = 1; i <= n; ++i) {
		apn += str[i] == 'N', pr_ += str[i] == '?', apc -= str[i] == 'C';
		for (i32 a = 0; a <= apn + pr_; ++a) {
			for (i32 c = 0; c <= apc + ap_ - pr_; ++c) {
				for (i32 sum = 0; sum <= k; ++sum) {
					if (str[i] == 'N' || str[i] == '?') {
						if (a && f[i - 1][a - 1][c][sum]) f[i][a][c][sum] = true, ch[i][a][c][sum] = 'N';
					}
					if (str[i] == 'A' || str[i] == '?') {
						if (a * c <= sum && f[i - 1][a][c][sum - a * c]) f[i][a][c][sum] = true, ch[i][a][c][sum] = 'A';
					}
					if (str[i] == 'C' || str[i] == '?') {
						if (c != n && f[i - 1][a][c + 1][sum]) f[i][a][c][sum] = true, ch[i][a][c][sum] = 'C';
					}
					if (str[i] != 'N' && str[i] != 'A' && str[i] != 'C' && str[i] != '?') {
						f[i][a][c][sum] = f[i - 1][a][c][sum], ch[i][a][c][sum] = str[i];
					}
				}
			}
		}
	}
	for (i32 i = apn; i <= apn + ap_; ++i)
		if (f[n][i][0][k]) return work(n, i, 0, k), 0;
	puts("-1");
	return 0;
}