func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     if (n <= 2) cout << -1;     if (n == 3) cout << 210;     if (n >= 4) {       string s =  1 ;       int sign;       int z = 0;       if (n % 3 == 0) z = 100;       if (n % 3 == 1) z = 1;       if (n % 3 == 2) z = 10;       if (((n - 1) / 3) % 2 == 0)         sign = 1;       else         sign = -1;       for (int i = 1; i < n; i++) s +=  0 ;       bool OK = false;       for (char i =  0 ; i <=  9 ; i++) {         for (char j =  0 ; j <=  9 ; j++) {           s[n - 2] = j;           s[n - 3] = i;           if (((1 + s[n - 2] -  0  + s[n - 3] -  0 ) % 3 == 0) &&               (((s[n - 3] -  0 ) * 100 + (s[n - 2] -  0 ) * 10 + z * sign) % 7 ==                0)) {             cout << s;             OK = true;             break;           }         }         if (OK) break;       }     }   }   