#include <bits/stdc++.h>   using namespace std;   vector<int> vi;   void primefact(int n) {     while (n % 2 == 0) {       vi.push_back(2);       n /= 2;     }     int i = 3;     while (i <= n) {       while (n % i == 0) {         vi.push_back(i);         n /= i;       }       i += 2;     }     if (n > 2) vi.push_back(n);   }   int main() {     int n, k, last = 1, i;     cin >> n >> k;     primefact(n);     if (k > vi.size())       cout <<  -1  << endl;     else {       for (i = 0; i < k - 1; i++) cout << vi[i] <<    ;       for (i = k - 1; i < vi.size(); i++) last *= vi[i];       cout << last;     }     return 0;   }   