#include <iostream>
#include <cmath>
using namespace std;

int main()
{
	int A, B, S, AS, BS;
	cin >> A >> B >> S;
	AS = abs(A - S);
	BS = abs(B - S);

	if (A == 0)
		cout << BS + S + 1;
	else if (AS <= BS)
		cout << AS + S;
	else if (S)
		cout << BS + S + A - 1;
	else
		cout << BS + AS + A;

	return 0;
}