#include <cstdio>
const int N = 100 + 10;
int n, m, c[N], p;
char h[N], a[N];
int main() {
    freopen("wheel.in", "r", stdin);
    freopen("wheel.out", "w", stdout);
    while(scanf("%d %d", &n, &m) == 2) {
        for(int i=0; i<n; i++) a[i] = '?';
        p = 0;
        for(int i=0; i<m; i++)
            scanf("%d %c", c+i, h+i);
        for(int i=0; i<m; i++) {
            p = (n + p - c[i] % n) % n;
            if(a[p] == '?') {
                a[p] = h[i];
            } else if(a[p] != h[i]) {
                printf("!\n");
                goto err;
            }
        }
        for(int i=0; i<n; i++)
            printf("%c", a[(p + i) % n]);
        printf("\n");
err:    ;
    }
    return 0;
}