#include <iostream>
#include <cmath>

using namespace std;
int main(void)
{
	int A,B,S;
	cin >> A >> B >> S;
	if(abs(S-A)<abs(S-B))
	{
		S = 2*S-A;
	}else
	{
		S=A+B-1;
	}
	cout << S << endl;
}