#include<iostream>
#include<cmath>
using namespace std;
int main() {
	long long a, b, c;
	cin >> a >> b >> c;
	long long ret = 0;
	if (a + c >= b && b + c >= a) {
		ret = max(a, b) + (c - abs(a - b)) / 2;
	}
	else {
		ret = min(a, b) + c;
	}
	long long l = 0, r = ret;
	while (l < r) {
		long long mid = (l + r + 1) / 2;
		if (mid * (mid + 1) / 2 <= ret) l = mid;
		else r = mid - 1;
	}
	cout << l;
	return 0;
}

为什么这个过不了啊，有啥问题呀