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

int n, m; 
char a[30];
    
int main()
{
    freopen("wheel.in", "r", stdin);
    freopen("wheel.out", "w", stdout);
        
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
            
    while(cin >> n >> m)
    {
        if(n == 0 && m == 0)
             break;
        fill(a+1,a+n+1,'?');
        int idx = 0;
        bool flag = true;
        for(int i = 1; i <= m; ++i)
        {
            int c;
            char ch;
            cin >> c >> ch;
            idx += c;
            idx %= n;
            if(idx == 0)
                idx = n;
            if(a[idx] == '?')
                a[idx] = ch;
            else if(a[idx] != ch)
            {
                cout << "!" << '\n';
                flag = false;
                break;
            }
        }
        if(flag == true)
        {
            for(int i = idx; i > 0; --i)
                cout << a[i];
            for(int i = n; i > idx; --i)
                cout << a[i];
            cout << '\n';
        }
    }
    
   	return 0;
}