代码如下：

#include <bits/stdc++.h>
#define ll long long int
using namespace std;
int main()
{
	ll a,b,c;
	cin >> a >> b >> c;
	if(c != 0)
	{
		if(a > b)
		{
			if(a - b <= c)
			{
				b = a;
				c = c - a + b;
				a = a + c / 2;
				b = b + c / 2;
				if(c % 2 != 0)
				{
					a++;
				}
			}
			else
			{
				b = b + c;
			}
		}
		else
		{
			if(b - a <= c)
			{
				a = b;
				c = c - b + a;
				a = a + c / 2;
				b = b + c / 2;
				if(c % 2 != 0)
				{
					a++;
				}
			}
			else
			{
				a = a + c;
			}
		}
	}
	ll i = 1;
	while(a - i >= 0 && b - i >= 0)
	{
		a = a - i;
		b = b - i;
		i++;
	}
	cout << i - 1 << endl;
	return 0;
}

提交记录：

https://www.luogu.com.cn/record/122350778