#include<iostream>
#include<cstdlib>

int main() {
	int a, b, s;

	std::cin >> a >> b >> s;

	int dist_a = std::abs(a - s),
		dist_b = std::abs(b - s);
	
	int ans;
	if (dist_a <= dist_b || dist_a == dist_b || s == 1) {
		ans = dist_a + s;
	} else {
		ans = dist_b;
		if (dist_a < s - 1) ans += dist_a;
		else ans += s - 1;
		if (a == 0) ans+=2;
		ans += a;
	}

	std::cout << ans << std::endl;
}