[백준]3009-네 번째 점(설명X)

#include <iostream>
using namespace std;
 
int main()
{
    int x1, x2, x3, y1, y2, y3, x4, y4;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    if (x1 == x2)
        x4 = x3;
    else if (x1 == x3)
        x4 = x2;
    else
        x4 = x1;
 
    if (y1 == y2)
        y4 = y3;
    else if (y1 == y3)
        y4 = y2;
    else
        y4 = y1;
    cout << x4 << " " << y4 << endl;
}