func_code_string: #include <bits/stdc++.h>   using namespace std;   int lsone(int n) { return (n & -n); }   void mult(long long int a[25][25], long long int b[25][25],             long long int c[25][25], int m, int n, int p) {     for (int i = 1; i <= m; i++) {       for (int j = 1; j <= p; j++) {         c[i][j] = 0;         for (int k = 1; k <= n; k++) {           c[i][j] += (a[i][k] * b[k][j]) % 1000000007;           c[i][j] %= 1000000007;         }       }     }   }   void mat_pow(long long int a[25][25], long long int c[25][25], int n,                long long int p) {     if (p == 0) {       for (int i = 1; i <= n; i++) c[i][i] = 1;     } else if (p == 1) {       for (int i = 1; i <= n; i++) {         for (int j = 1; j <= n; j++) c[i][j] = a[i][j];       }     } else {       long long int d[25][25];       mat_pow(a, d, n, p / 2);       if (p % 2) {         long long int e[25][25];         mult(d, d, e, n, n, n);         mult(e, a, c, n, n, n);       } else {         mult(d, d, c, n, n, n);       }     }   }   long long int pow1(long long int a, long long int b) {     if (b == 0)       return 1ll;     else if (b == 1)       return a;     else {       long long int x = pow1(a, b / 2);       x *= x;       x %= 1000000007;       if (b % 2) {         x *= a;         x %= 1000000007;       }       return x;     }   }   int n, ans[110000];   int s(int y) {     int ans = 0;     while (y) {       y /= 10;       ans++;     }     return ans;   }   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     ;     ans[1] = 1;     for (int i = 2; i <= 1e5; i++) {       ans[i] = ans[i - 1] * 10;       ans[i] %= 210;     }     cin >> n;     int req = (210 - ans[n]) % 210;     if (n <= 2) {       cout << -1 <<   n ;     } else if (n == 3)       cout << 210 <<   n ;     else {       int numdig = s(req);       cout << 1;       for (int i = 0; i < n - numdig - 1; i++) cout << 0;       cout << req <<   n ;     }     return 0;   }   