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

const int N = 50;

char pan[N];

int n,m;

int main(){
    freopen("wheel.in","r",stdin);
    freopen("wheel.out","w",stdout);
    while(cin>>n>>m){
        int boo=0;
            int now=0;
    memset(pan,0,sizeof(pan));
    for(int i=1;i<=m;i++){
        int ci;
        char chi;
        cin>>ci>>chi;
        now+=ci;
        now%=n;
        if(pan[now]!=0&&pan[now]!=chi){
            cout<<"!"<<endl;
            boo=1;
        }else{
            pan[now]=chi;
        }
    }
    if(boo==1)continue;
    for(int i=n;i>0;i--){
        int u=(now+i)%n;
        if(pan[u]!=0)cout<<pan[u];
        else cout<<'?';
    }
    cout<<endl;
    }
    return 0;
}