#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	int X, Y, R;
	cin >> X >> Y >> R;
	X = abs(X);
	Y = abs(Y);
	int l = X + Y, r = 1000;
	while (r - l > 1) {
		int m = l + r >> 1;
		// x_0 = (m + X - Y) / 2, y_0 = m - x_0
		auto func = [](int x1, int y1, int x2, int y2) {
			return (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1);
		};
		int dist2 = func(m + X - Y, 2 * m - (m + X - Y), 2 * X, 2 * Y);
		if (dist2 > R * R * 4) r = m;
		else l = m;
	}
	cout << r << endl;
}