10242 - Fourth Point !!

/*
+---------------------------------------------+
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|       © 17/04/2023 (18:14) MinaMagdy        |
|                                             |
+---------------------------------------------+
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define multi_ordered_set tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>
#define endl "\n"
#define MOD 1000000007
#define INF 2000000000
#define all(s) s.begin(), s.end()
#define rall(s) s.rbegin(), s.rend()
#define sz(x) int(x.size())

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
// --------------------------->         GEOMETRY         <---------------------------
#define EPS 1e-9
#define PI acos(-1)
#define X real()
#define Y imag()
#define angle(a) atan2(a.Y, a.X)
#define vec(a, b) point((b) - (a))
#define length(a) hypot(a.Y, a.X)
#define normalize(a) (a) / length(a)
#define dot_prod(a, b) real(conj(a) * (b))
#define cross_prod(a, b) imag(conj(a) * (b))
#define lengthSqr(p) dot_prod(p, p)
#define rotateO(p, ang) p * exp(point(0, ang))
#define rotateA(p, about, ang) rotateO(vec((about), (p)), ang) + (about)
#define reflicatO(v, m) conj(v / m) * m
#define reflicatA(v, about, m) conj(vec(about, v) / vec(about, m)) * vec(about, m) + about

typedef complex<ld> point;
bool cin_point(point &p) {
    double x = -INF, y = -INF;
    cin >> x >> y;
    p = {x, y};
    return x != -INF or y != -INF;
}

void solve() {
    ld x1, y1, x2, y2, x3, y3, x4, y4;
    while (scanf("%Lf %Lf %Lf %Lf %Lf %Lf %Lf %Lf", &x1, &y1, &x2, &y2, &x3, &y3, &x4, &y4) != EOF) {
        vector<point> p = {{x1, y1}, {x2, y2}, {x3, y3}, {x4, y4}};
        sort(all(p), [](point a, point b) {
            if (a.X == b.X) return a.Y < b.Y;
            return a.X < b.X;
        });
        point ans;
        if (p[0] == p[1]) {
            ans = p[2] + p[3] - p[0];
        }
        else if (p[1] == p[2]) {
            ans = p[0] + p[3] - p[1];
        }
        else if (p[2] == p[3]) {
            ans = p[0] + p[1] - p[2];
        }
        cout << fixed << setprecision(3) << ans.X << " " << ans.Y << endl;
    }
}

int main(void)
{
    ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
    int testcase = 1;
    // cin >> testcase;
    while (testcase--)
        solve();
    return 0;
}