#include<bits/stdc++.h>
using namespace std;
int n,m;
int main(){
    freopen("wheel.in","r",stdin);
    freopen("wheel.out","w",stdout);
    while(cin>>n){
        deque<char> q;
        cin>>m;
        for(int i=1;i<=n;i++){
            q.push_back('?');
        }
        int flag=1;
        while(m--){
            int cs;
            char c;
            cin>>cs>>c;
            if(flag==0){
                continue;
            }
            for(int i=1;i<=cs;i++){
                q.push_front(q.back());
                q.pop_back();
            }
            if(q.front()!='?'&&q.front()!=c){
                flag=0;
            }else{
                q.pop_front();
                q.push_front(c);
            }
        }
        if(!flag){
            cout<<"!\n";
        }
        else{
            while(q.size()){
                cout<<q.front();
                q.pop_front();
            }
            cout<<"\n";
        }
    }
    return 0;
}