#include <bits/stdc++.h>
using namespace std;

int N,m;
int a[30];
bool d[30],f;

int main(){
    freopen("wheel.in","r",stdin);
    freopen("wheel.out","w",stdout);
    
    cin.tie(0);cout.tie(0);
    
    int p;
    char ch;
    long long c,r;
    while (cin>>N>>m){
        memset(a,0,sizeof(a));
        memset(d,0,sizeof(d));
        f=0,c=0;
        for (int i=1;i<=m;i++){
            cin>>r>>ch;
            c+=r;
            c=c%(long long)N;
            if (!c) c=N;
            ch-='A'-1;
            if ((d[ch] || a[c]) && a[c]!=ch){
                f=1;
                break;
            }
            d[ch]=1,a[c]=ch;
        }
        if (f){
            printf("!\n");
        }
        else {
            for (int i=c;i>=1;i--){
                if (a[i]) cout<<(char)(a[i]+'A'-1);
                else cout<<'?';
            }
            for (int i=N;i>c;i--){
                if (a[i]) cout<<(char)(a[i]+'A'-1);
                else cout<<'?';
            }
            cout<<'\n';
        }
    }
    
    return 0;
}