#include <iostream>
#include <cmath>

void solve() {
    int x, y, r;
    std::cin >> x >> y >> r;
    int s = std::abs(x) + std::abs(y);

    int ok = 10000, ng = s;
    while (ok - ng > 1) {
        int mid = (ok + ng) / 2;
        if (2 * r * r < (mid - s) * (mid - s)) {
            ok = mid;
        } else {
            ng = mid;
        }
    }

    std::cout << ok << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}