向量法求垂直(思维)

#include <bits/stdc++.h>

using i64 = long long;

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);

	i64 xa, ya, xb, yb;
	std::cin >> xa >> ya >> xb >> yb;

	i64 dx = ya - yb, dy = xb - xa;
	xa += xb - dx, ya += yb - dy;

	if (xa & 1 || ya & 1) {
		std::cout << "No" << " " << "Answer!" << "\n";
	}
	else {
		std::cout << xa / 2 << " " << ya / 2 << "\n";
	}
	
	return 0;
}