#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    vector<pair<int,int>> a(3), S;
    for(auto &&[y, x] : a) cin >> y >> x;
    auto f = [&](int y, int x, int p){
        auto [y2, x2] = a[p];
        return abs(y - y2) + abs(x - x2);
    };
    for(int y = -2000; y <= 2000; y++){
        for(int x = -2000; x <= 2000; x++){
            if(f(y, x, 0) == f(y, x, 1) && f(y, x, 1) == f(y, x, 2)){
                S.emplace_back(y, x);
                if(abs(y) > 1000 || abs(x) > 1000){
                    cout << "-1\n";
                    return 0;
                }
            }
        }
    }
    cout << S.size() << '\n';
    for(auto [y, x] : S) cout << y << " " << x << "\n";
}