#include <bits/stdc++.h>
using namespace std;
int n,m;
char s[1010];
int main () {
    freopen("wheel.in","r",stdin);
    freopen("wheel.out","w",stdout);
    while (cin >> n >> m) {
        memset(s,' ',sizeof(s));
        int cnt=0,flag=0;
        for (int i=1;i<=m;i++) {
            char a;
            int b;
            cin >> b >> a;
            cnt+=b;
            cnt%=n;
            if (s[cnt]!=' '&&s[cnt]!=a) {
                flag=1;
            }else{
                s[cnt]=a;
            }
        }
        if (flag==0) {
            for (int i=0;i<n;i++) {
                int t=(cnt-i+n)%n;
                if (s[t]==' ') cout << "?";
                else cout << s[t];
            }
            cout <<endl;
        }else{
            cout << "!" <<endl; 
        }
    }
    return 0;
}