#include <bits/stdc++.h>   using namespace std;   int cmpfunc(const void *a, const void *b) { return (*(int *)a - *(int *)b); }   long long int gcd(long long int m, long long int n) {     if (n == 0) return m;     return gcd(n, m % n);   }   long long int fastpow(long long int a, long long int b, long long int m) {     long long int r = 1;     while (b > 0) {       if (b % 2 == 1) r = (r * a) % m;       b = b >> 1;       a = (a * a) % m;     }     return r;   }   int prime(long long int x) {     if (x == 1) return 0;     if (x <= 3) return 1;     if (x % 6 == 1 || x % 6 == 5) {       long long int y = sqrt(x), i;       for (i = 2; i <= y; i++)         if (x % i == 0) return 0;       return 1;     }     return 0;   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(NULL);     long long int n, t;     cin >> n >> t;     if (n == 1 && t == 10)       cout << -1 << endl;     else if (t <= 9) {       for (long long int i = 0; i < n; i++) cout << t;       cout << endl;     } else {       cout << 1;       for (long long int i = 1; i < n; i++) cout << 0;       cout << endl;     }     return 0;   }   