#pragma GCC optimize(2)
#include<bits/stdc++.h>
#define ll long long
#define N 45
#define M 2505
using namespace std;
ll n,m;
char c[N],ji[N];
bool p=true;
bitset<M>dp[N][N][N*N];
void dfs(ll f,ll i,ll k,ll j){
    if(!dp[f][i][k][j])return;
    if(!f){
        for(i=1;i<=n;i++)cout<<ji[i];
        p=false;
        exit(0);
    }
    if((c[f]=='N'||c[f]=='?')&&i){ji[f]='N';
        dfs(f-1,i-1,k,j);
    }
    if((c[f]=='A'||c[f]=='?')&&k>=i){ji[f]='A';
        dfs(f-1,i,k-i,j);

    }
    if((c[f]=='C'||c[f]=='?')&&j>=k){ji[f]='C';
        dfs(f-1,i,k,j-k);
    }
    if(c[f]!='A'&&c[f]!='N'&&c[f]!='C'){
        if(c[f]=='?')ji[f]='T';
        else ji[f]=c[f];
        dfs(f-1,i,k,j);
    }
}
int main(){ll i,k,j;
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);
    cin>>n>>m>>c+1;
    dp[0][0][0][0]=1;
    for(i=1;i<=n;i++){
        for(k=0;k<=i;k++){
            for(j=0;j<=i*i;j++){
                if((c[i]=='N'||c[i]=='?')&&k)dp[i][k][j]|=dp[i-1][k-1][j];
                if((c[i]=='A'||c[i]=='?')&&j>=k)dp[i][k][j]|=dp[i-1][k][j-k];
                if(c[i]=='C'||c[i]=='?')dp[i][k][j]|=(dp[i-1][k][j]<<j);
                if(c[i]!='N'&&c[i]!='A'&&c[i]!='C')dp[i][k][j]|=dp[i-1][k][j];
            }
        }
    }
    for(i=0;i<=n;i++){
        for(k=0;k<=n*n;k++){
            if(dp[n][i][k][m]){
                dfs(n,i,k,m);
            }
        }
    }
    cout<<-1;
}