#include<bits/stdc++.h>
#define il inline
#define ui unsigned int
#define ll long long
#define ull unsigned ll
#define lll __int128
#define db double
#define ldb long double
#define pii pair<int,int>
#define vi vector<int>
#define vpii vector<pii>
#define fir first
#define sec second
#define gc getchar
#define pc putchar
#define mst(a,x) memset(a,x,sizeof a)
#define mcp(a,b) memcpy(a,b,sizeof b)
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define pct __builtin_popcount
using namespace std;
const int N=45,M=2510,INF=0x3f3f3f3f,MOD=1e9+7; const ll INFll=0x3f3f3f3f3f3f3f3f;
il int rd() {int x=0,f=1; char ch=gc(); while(ch<'0'||ch>'9') {if(ch=='-') f=-1; ch=gc();} while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=gc(); return x*f;}
il ll rdll() {ll x=0; int f=1; char ch=gc(); while(ch<'0'||ch>'9') {if(ch=='-') f=-1; ch=gc();} while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=gc(); return x*f;}
il void wr(int x) {if(x<-2147483647) {printf("-2147483648"); return;} if(x<0) {pc('-'),wr(-x); return;} if(x<10) {pc(x+'0'); return;} wr(x/10),pc(x%10+'0');}
il void wrll(ll x) {if(x<-9223372036854775807) return (void)printf("-9223372036854775808"); if(x<0) return pc('-'),wrll(-x); if(x<10) return (void)pc(x+'0'); wrll(x/10),pc(x%10+'0');}
il void wr(int x,char *s) {wr(x),printf("%s",s);}
il void wrll(ll x,char *s) {wrll(x),printf("%s",s);}
il int vmod(int x) {return x>=MOD?x-MOD:x;}
il int vadd(int x,int y) {return vmod(x+y);}
il int vsub(int x,int y) {return vmod(x-y+MOD);}
il int vmul(int x,int y) {return 1ll*x*y%MOD;}
il int qpow(int x,int y) {int res=1; for(;y;y>>=1,x=vmul(x,x)) if(y&1) res=vmul(res,x); return res;}
il void cadd(int &x,int y) {x=vmod(x+y);}
il void csub(int &x,int y) {x=vmod(x-y+MOD);}
il void cmax(int &x,int y) {x<y&&(x=y);}
il void cmin(int &x,int y) {x>y&&(x=y);}
int n,m; string s; bitset<M> dp[N][N][N*N];
void QwQ() {
	n=rd(),m=rd(),cin>>s,dp[0][0][0]=1;
	for(int i=0;i<n;i++) for(int j=0;j<=n;j++) for(int k=0;k<=n*n;k++) {
		if(s[i]=='N'||s[i]=='?') dp[i+1][j+1][k]|=dp[i][j][k];
		if(s[i]=='A'||s[i]=='?') dp[i+1][j][k+j]|=dp[i][j][k];
		if(s[i]=='C'||s[i]=='?') dp[i+1][j][k]|=dp[i][j][k]<<k;
		if(s[i]!='N'&&s[i]!='A'&&s[i]!='C'&&s[i]!='?') dp[i+1][j][k]|=dp[i][j][k];
	}
	for(int p=0;p<=n;p++) for(int q=0;q<=n*n;q++) if(dp[n][p][q][m]) {
		for(int i=n-1;~i;i--) {
			if(s[i]=='?') {if(p&&dp[i][p-1][q][m]) p--,s[i]='N'; else if(q>=p&&dp[i][p][q-p][m]) q-=p,s[i]='A'; else if(m>=q&&dp[i][p][q][m-q]) m-=q,s[i]='C'; else s[i]='X';}
			else if(s[i]=='N') p--; else if(s[i]=='A') q-=p; else if(s[i]=='C') m-=q;
		}
		cout<<s<<"\n",exit(0);
	}
	puts("-1");
}
signed main() {
	int T=1; while(T--) QwQ();
}
/*
22 2
N??A??????C???????????

18 0
COUNTINGSATELLITES

2 1
??
*/