#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N=1e5;
void solve() {
    int n,k;cin>>n>>k;
    string s;cin>>s;s="#"+s;
    vector<vector<set<array<int,3>>>>f(n+1,vector<set<array<int,3>>>(4));
    f[0][0].insert({0,0,0});f[0][1].insert({0,0,0});f[0][2].insert({0,0,0});f[0][3].insert({0,0,0});
    for(int i=1;i<=n;i++){
        for(int j=0;j<4;j++){
            for(auto [a1,a2,a3]:f[i-1][j]){
                if(s[i]=='N')f[i][0].insert({a1+1,a2,a3});
                else if(s[i]=='A')f[i][1].insert({a1,a1+a2,a3});
                else if(s[i]=='C')f[i][2].insert({a1,a2,a2+a3});
                else if(s[i]=='?'){
                    f[i][0].insert({a1+1,a2,a3});
                    f[i][1].insert({a1,a1+a2,a3});
                    f[i][2].insert({a1,a2,a2+a3});
                    f[i][3].insert({a1,a2,a3});
                }
                else f[i][3].insert({a1,a2,a3});
            }
        }
    }
    char last='#';
    int l1,l2,l3;
    if(s[n]=='N'){
        for(auto [a1,a2,a3]:f[n][0])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='N';
            }
    }
    else if(s[n]=='A'){
        for(auto [a1,a2,a3]:f[n][1])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='A';
            }
    }
    else if(s[n]=='C'){
        for(auto [a1,a2,a3]:f[n][2])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='C';
            }
    }
    else if(s[n]=='?'){
        for(auto [a1,a2,a3]:f[n][0])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='N';
            }
        for(auto [a1,a2,a3]:f[n][1])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='A';
            }
        for(auto [a1,a2,a3]:f[n][2])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='C';
            }
        for(auto [a1,a2,a3]:f[n][3])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='?';
            }
    }
    else{
        for(auto [a1,a2,a3]:f[n][3])
            if(a3==k){
                l1=a1;l2=a2;l3=a3;
                last='?';
            }
    }
    if(last=='#'){
        cout<<"-1\n";
        return;
    }
    if(s[n]=='?')s[n]=last;
    if(s[n]=='?')s[n]='E';
    //cout<<l1<<" "<<l2<<" "<<l3<<"\n";
    for(int i=n-1;i>0;i--){
        bool flag=0;
        for(int j=0;j<4;j++){
            if(flag)break;
            for(auto [a1,a2,a3]:f[i][j]){
                if(flag)break;
                int n1=a1,n2=a2,n3=a3;
                if(last=='N')n1++;
                else if(last=='A')n2+=n1;
                else if(last=='C')n3+=n2;
                if(n1==l1&&n2==l2&&n3==l3){
                    l1=a1;l2=a2;l3=a3;
                    if(j==0)last='N';
                    if(j==1)last='A';
                    if(j==2)last='C';
                    if(j==3)last='?';
                    flag=1;
                }
            }
        }
        if(s[i]=='?')s[i]=last;
        if(s[i]=='?')s[i]='E';
        //cout<<l1<<" "<<l2<<" "<<l3<<"\n";
    }
    s.erase(s.begin());
    cout<<s<<"\n";
}

/**
22 2
N??A??????C???????????
18 0
COUNTINGSATELLITES
2 1
??
 * **/
signed main() {
//    std::ios::sync_with_stdio(false);
//    std::cin.tie(nullptr);
    int t = 1;
    //std::cin >> t;
    for (int i = 0; i < t; ++i) {
        solve();
    }
    return 0;
}