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