#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin >> n;
    if(n == 1){
        cout << -1;
        return 0;
    }
    if(n % 2 == 0){
        for(int i = 0; i < n; i += 2){
            cout << 1;
        }
    }else{
        cout << 7;
        n -= 3;
        for(int i = 0; i < n; i += 2){
            cout << 1;
        }
    }
    return 0;
}
