#include<bits/stdc++.h>
using namespace std;
const int N=30,M=110;
char c[N];
int n,m;
struct xw
{
	long long c;
	char ch;
}xs[M];
int w;
bool flag;
int main()
{
	freopen("wheel.in","r",stdin);
	freopen("wheel.out","w",stdout);
	while(cin>>n>>m)
	{
		for(int i=1;i<=m;i++)
		{
			scanf("%lld",&xs[i].c);
			cin>>xs[i].ch;
		}
		w=1;
		for(int i=m;i>=1;i--)
		{
			if(c[w]&&c[w]!=xs[i].ch)
			{
				flag=1;
				break;
			}
			c[w]=xs[i].ch;
			w=(w-1+xs[i].c%n)%n+1;
		}
		if(flag) printf("!\n");
		else
		{
			for(int i=1;i<=n;i++)
			{
				if(c[i]==0) printf("?");
				else cout<<c[i];
			}
			printf("\n");
		}
		memset(c,0,sizeof(c));
		flag=0;
	}
	return 0;
}