// what is matter? never mind. 
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
#define int long long
#define ull unsigned long long
#define SZ(x) ((int)((x).size()))
#define ALL(x) (x).begin(),(x).end()
using namespace std;
inline int read()
{
	char c=getchar();int x=0;bool f=0;
	for(;!isdigit(c);c=getchar())f^=!(c^45);
	for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
	if(f)x=-x;return x;
}

int mod;
struct modint{
	int x;
	modint(int o=0){x=o;}
	modint &operator = (int o){return x=o,*this;}
	modint &operator +=(modint o){return x=x+o.x>=mod?x+o.x-mod:x+o.x,*this;}
	modint &operator -=(modint o){return x=x-o.x<0?x-o.x+mod:x-o.x,*this;}
	modint &operator *=(modint o){return x=1ll*x*o.x%mod,*this;}
	modint &operator ^=(int b){
		modint a=*this,c=1;
		for(;b;b>>=1,a*=a)if(b&1)c*=a;
		return x=c.x,*this;
	}
	modint &operator /=(modint o){return *this *=o^=mod-2;}
	friend modint operator +(modint a,modint b){return a+=b;}
	friend modint operator -(modint a,modint b){return a-=b;}
	friend modint operator *(modint a,modint b){return a*=b;}
	friend modint operator /(modint a,modint b){return a/=b;}
	friend modint operator ^(modint a,int b){return a^=b;}
	friend bool operator ==(modint a,modint b){return a.x==b.x;}
	friend bool operator !=(modint a,modint b){return a.x!=b.x;}
	bool operator ! () {return !x;}
	modint operator - () {return x?mod-x:0;}
	bool operator <(const modint&b)const{return x<b.x;}
};
inline modint qpow(modint x,int y){return x^y;}

vector<modint> fac,ifac,iv;
inline void initC(int n)
{
	if(iv.empty())fac=ifac=iv=vector<modint>(2,1);
	int m=iv.size(); ++n;
	if(m>=n)return;
	iv.resize(n),fac.resize(n),ifac.resize(n);
	For(i,m,n-1){
		iv[i]=iv[mod%i]*(mod-mod/i);
		fac[i]=fac[i-1]*i,ifac[i]=ifac[i-1]*iv[i];
	}
}
inline modint C(int n,int m){
	if(m<0||n<m)return 0;
	return initC(n),fac[n]*ifac[m]*ifac[n-m];
}
inline modint sign(int n){return (n&1)?(mod-1):(1);}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 400045
#define inf 0x3f3f3f3f

bool mbe;
int n,nd;
bitset<2505> f[42][42][42*42/2];
char s[maxn];
bool med;

bool isok(char c,char d){
	return c=='?' || c==d;
}
char res[maxn];
// N A C

void print(int u,int j,int k,int nd){
	if(!u)return;
	int i=u;
	if(isok(s[i],'N') && j && f[u-1][j-1][k][nd]) return res[i]='N',print(u-1,j-1,k,nd);
	if(isok(s[i],'A') && k>=j && f[u-1][j][k-j][nd]) return res[i]='A',print(u-1,j,k-j,nd);
	if(isok(s[i],'C') && nd>=k && f[u-1][j][k][nd-k]) return res[i]='C',print(u-1,j,k,nd-k);
	For(ch,'A','Z') if(isok(s[i],ch) && ch!='A' && ch!='N' && ch!='C') return res[i]=ch,print(u-1,j,k,nd);
}
signed main()
{
//	cout<<(1.0*(&mbe-&med)/1024576.0)<<"\n";
	n=read(),nd=read();
	f[0][0][0]=1;
	cin>>(s+1);
	For(i,1,n){
		For(j,0,i-1){
			For(k,0,(i-1)*(i-2)/2){
				// f[i-1][j][k].
				if(!f[i-1][j][k].any()) continue;
				if(isok(s[i],'N')){
					f[i][j+1][k]|=f[i-1][j][k];
				}
				if(isok(s[i],'A')){
					f[i][j][k+j]|=f[i-1][j][k];
				}
				if(isok(s[i],'C')){
					f[i][j][k]|=(f[i-1][j][k]<<k);
				}
				if(s[i]!='N' && s[i]!='A' && s[i]!='C'){
					f[i][j][k]|=f[i-1][j][k];
				}
			}
		}
	}
	int jj=-1,kk=-1;
	For(j,0,n)
		For(k,0,n*(n-1)/2)
			if(f[n][j][k][nd]) jj=j,kk=k;
	if(jj==-1){
		puts("-1");
		exit(0);
	}
	print(n,jj,kk,nd);
	For(i,1,n) putchar(res[i]);
	return 0;
}
/*


10 10
1 2 2 2 5 2 3 4 3 
1 10 5 7
2 4 3 4 5 6 
*/