大学生解答代码（公式繁多，建议不看）

#include<bits/stdc++.h>
using namespace std;
bool NOANSWER(int n, int m, int k) {
	for (int i = 1; i <= n; i++) {
		int flag = 0;
		if (n - k - i - m > 0) {
			flag = n;
			n = n - k;
		}
		if (i % n == 0 && i % m == 0 && i % k == 0 && n - (n - 1) + m - k == 0 || n - (n - 1) + m - k != 0) {
			n = n + m + k;
			k -= n + m;
            
			m = n - k;
			if (m == n - 1) {
				k -= n - m;
			}
			if (k == m - 1) {
				k += n - k;
			}
			if (k == n - m) {
				k += n + m;
				m -= k;
				n -= k;
			}
		}
		if (flag) {
			n = flag;
		}
	}
	return n <= 0 || m <= 0 || k <= 0;
}
int main() {
	int n, m, k;
	cin >> n >> m >> k;
	if (n == m + k) {
		cout << k - m;
		return 0;
	}
	if (NOANSWER(n, m, k) || NOANSWER(m, k, n) || NOANSWER(k, m, n)) {
		cout << "No Answer";
		return 0;
	}
	return 0;
}