#include<bits/stdc++.h>
using namespace std;
int n,m;
char a[26];
int main(){
	freopen("wheel.in","r",stdin);
	freopen("wheel.out","w",stdout);
	while(cin>>n>>m){
		int c,u=1;
		bool flag=1;
		char ch;
		memset(a,0,sizeof(a));
		for(int i=1;i<=m;i++){
			cin>>c>>ch;
			u+=c;
			if(!flag) continue ;
			if(u>n){
				u-=n;
			}
			if(a[u]==0){
				a[u]=ch;
			}
			else if(a[u]!=ch){
				flag=0;
			}
		}
		if(!flag){
			cout<<'!'<<endl;
			continue ;
		}
		for(int i=1;i<=n;i++){
			if(a[u]!=0){
				cout<<a[u];
			}
			else{
				cout<<'?';
			}
			u--;
			if(u<1){
				u+=n;
			}
		}
		cout<<endl;
	}
	return 0;
}