#include<bits/stdc++.h>
using namespace std;
const int maxn=42;
const int maxnn=410;
const int maxm=2510;

struct data{int i,j,k,l,c;};
int n,m,n2,n3;
char s[maxn],t[maxn];
int f[22][22][110][260];
int pf[200010],fcnt;
bitset<260> fb[22][110];
int g[22][22][110][260];
int pg[200010],gcnt;
bitset<260> gb[22][110];
int id(data x){return x.c*22*22*110*260+x.i*22*110*260+x.j*110*260+x.k*260+x.l;}
data reid(int x){return (data){x/(22*110*260)%22,x/(110*260)%22,x/260%110,x%260,x/(22*22*110*260)};}
void solve(){
	n2=n/2;
	memset(f,-1,sizeof(f));
	f[0][0][0][0]=0;
	for(int i=0;i<n2;i++)
	for(int j=0;j<=i;j++)
	for(int k=0;k<=(i-j)*j;k++)
	for(int l=0;l<=(j>0?(i-j-k/j)*k:0);l++){
		if(f[i][j][k][l]==-1) continue;
		if(s[i+1]=='N'||s[i+1]=='?')
		f[i+1][j+1][k][l]=id((data){i,j,k,l,1});
		if(s[i+1]=='A'||s[i+1]=='?')
		f[i+1][j][k+j][l]=id((data){i,j,k,l,2});
		if(s[i+1]=='C'||s[i+1]=='?')
		f[i+1][j][k][l+k]=id((data){i,j,k,l,3});
		if(s[i+1]=='?')
		f[i+1][j][k][l]=id((data){i,j,k,l,0});
	}
	for(int j=0;j<=n2;j++)
	for(int k=0;k<=(n2-j)*j;k++)
	for(int l=0;l<=(j>0?(n2-j-k/j)*k:0);l++) if(f[n2][j][k][l]!=-1)
	pf[++fcnt]=id((data){n2,j,k,l,0});
}
void solve2(){
	n3=n-n2;
	memset(g,-1,sizeof(g));
	g[0][0][0][0]=0;
	for(int i=0;i<n3;i++)
	for(int j=0;j<=i;j++)
	for(int k=0;k<=(i-j)*j;k++)
	for(int l=0;l<=(j>0?(i-j-k/j)*k:0);l++){
		if(g[i][j][k][l]==-1) continue;
		if(s[n-i]=='C'||s[n-i]=='?')
		g[i+1][j+1][k][l]=id((data){i,j,k,l,3});
		if(s[n-i]=='A'||s[n-i]=='?')
		g[i+1][j][k+j][l]=id((data){i,j,k,l,2});
		if(s[n-i]=='N'||s[n-i]=='?')
		g[i+1][j][k][l+k]=id((data){i,j,k,l,1});
		if(s[n-i]=='?')
		g[i+1][j][k][l]=id((data){i,j,k,l,0});
	}
	for(int j=0;j<=n3;j++)
	for(int k=0;k<=(n3-j)*j;k++)
	for(int l=0;l<=(j>0?(n3-j-k/j)*k:0);l++) if(g[n3][j][k][l]!=-1)
	pg[++gcnt]=id((data){n3,j,k,l,0});
}
data ans1,ans2;
bool check(int x){
	data tmp=reid(x);
	int i=tmp.i,j=tmp.j,k=tmp.k,l=tmp.l;
	for(int x=0;x*k+l<=m&&x<=n3;x++)
	for(int y=0;x*k+y*j+l<=m&&y<=(n3-x)*x;y++){
		int z=m-(x*k+y*j+l);if(z>=260) continue;
		if(g[n3][x][y][z]!=-1){
			ans1=tmp;ans2=(data){n3,x,y,z,0};
			return 1;
		}
	}return 0;
}
int scnt;
char ch[4]={'D','N','A','C'};
void prf(data p){
	if(p.i==0&&p.j==0&&p.k==0&&p.l==0) return ;
	prf(reid(f[p.i][p.j][p.k][p.l]));//printf("%c",ch[reid(f[p.i][p.j][p.k][p.l]).c]);
	s[++scnt]=ch[reid(f[p.i][p.j][p.k][p.l]).c];
}
void prg(data p){
	if(p.i==0&&p.j==0&&p.k==0&&p.l==0) return ;
	//printf("%c",ch[reid(g[p.i][p.j][p.k][p.l]).c]);
	s[++scnt]=ch[reid(g[p.i][p.j][p.k][p.l]).c];
	prg(reid(g[p.i][p.j][p.k][p.l]));
}

int main(){
	scanf("%d%d",&n,&m);int tn=n;
	scanf("%s",s+1);for(int i=1;i<=n;i++) t[i]=s[i];
	for(int i=1,j=0;i<=n;i++){
		if(s[i]=='N'||s[i]=='A'||s[i]=='C'||s[i]=='?') s[++j]=s[i];
		if(i==n) n=j;
	}for(int i=n+1;i<maxn;i++) s[i]=0;
	if(n<3&&m>0){printf("-1\n");return 0;}
	solve();solve2();
	for(int i=1;i<=fcnt;i++) if(check(pf[i])){
		prf(ans1);prg(ans2);
		for(int j=1,k=0;j<=tn;j++){
			if(t[j]=='N'||t[j]=='A'||t[j]=='C'||t[j]=='?') printf("%c",s[++k]);
			else printf("%c",t[j]);
		}printf("\n");
		return 0;
	}printf("-1\n");
	return 0;
}
/*
int cnt=0;
for(int a=0;a<=20;a++)
for(int b=a;b<(20-a)*a;b++)
for(int c=0;c<=20;c++)
for(int d=c;d<=(20-c)*c&&a*b+c*d<=2500;d++)
for(int e=0;e<(20-a-b/a)*b&&a*b+c*d+e<=2500;e++) cnt++;
printf("%d\n",cnt);*/