//Shirosaki Hana kawaii
#include<bits/stdc++.h>
using namespace std;
inline int read(){
    int x=0,f=1; char ch=getchar();
    for (;ch<'0'||ch>'9';ch=getchar())
        if (ch=='-') f=-1;
    for (;ch>='0'&&ch<='9';ch=getchar())
        x=(x<<1)+(x<<3)+(ch^48);
    return x*f;
} 
int n,K; char ch[44],res[44];
bitset<2505> f[41][44][44];
signed main(){
	n=read(),K=read(),scanf("%s",ch+1);
	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-j;k++){
		if (ch[i]^'N'&&ch[i]^'A'&&ch[i]^'C') f[i][j][k]|=f[i-1][j][k];
		if (ch[i]=='N'||ch[i]=='?') if (j) f[i][j][k]|=f[i-1][j-1][k];
		if (ch[i]=='A'||ch[i]=='?') f[i][j][k]|=f[i-1][j][k]<<(j*k);
		if (ch[i]=='C'||ch[i]=='?') f[i][j][k]|=f[i-1][j][k+1];
	}
	for (int cn=0;cn<=n;cn++)
		if (f[n][cn][0][K]){
			for (int i=n,j=cn,k=0,r=K;i;i--)
				if (ch[i]=='N'||(j&&ch[i]=='?'&&f[i-1][j-1][k][r])) res[i]='N',j--;
				else if (ch[i]=='C'||(ch[i]=='?'&&f[i-1][j][k+1][r])) res[i]='C',k++;
				else if (ch[i]=='A'||(r>=j*k&&ch[i]=='?'&&f[i-1][j][k][r-j*k])) res[i]='A',r-=j*k;
				else res[i]=ch[i]=='?' ? (i&1 ? 'J':'K'):ch[i];
			printf("%s",res+1);
			return 0;
		}
	printf("-1");
	return 0;
}