#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, t, i;
  while (scanf("%d%d", &n, &t) == 2) {
    if (n == 1 && t > 9) {
      printf("-1\n");
      continue;
    }
    if (t == 10) {
      printf("1");
      for (i = 0; i < n - 1; i++) printf("0");
      printf("\n");
      continue;
    }
    for (i = 0; i < n; i++) printf("%d", t);
    printf("\n");
  }
  return 0;
}
