#include <bits/stdc++.h>

using namespace std;

#define int long long
#define pb push_back
#define in insert
#define f first
#define s second
#define all(x) x.begin(), x.rbegin()
#define allr(x) x.rbegin(), x.rend()

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n, m, t;
	cin >> n >> m >> t;
    /*int ans = 0;
	for (int i = 1; i <= min(n / 2, m / 2); i++) {
		if (t >= -4 * i * i + 2 * i * (n + m)) {
			ans = i;
		}
	}
	cout << ans << endl;
	ans = 0;*/
	vector<int> ans;
	int D = (2 * (n + m)) * (2 * (n + m)) - 16 * t;
	if (D >= 0) {
        int sqr = sqrt(D);
        vector<int> ansv;
        ansv.pb((-2 * (n + m)) + sqr);
        ansv.pb((-2 * (n + m)) + sqr + 1);
        for (auto now : ansv) {
            int now_ans = now / -8;
            ans.pb(now_ans);
            now_ans++;
            ans.pb(now_ans);
        }
	}
	int gg = 0;
	for (auto i : ans) {
        if (i >= 0 && i <= min(n / 2, m / 2) && t >= -4 * i * i + 2 * i * (n + m)) {
            gg = max(gg, i);
        }
	}
	cout << gg;
	return 0;
}