#include <iostream>
#include <stdlib.h>

int main()
{
    int a, b, s;
    int move = 0;
    std::cin >> a >> b >> s;
    
    int as = abs(a - s);
    int bs = abs(b - s);
    
    if((s == 1) || (as <= bs))
    {
        move += as + s;
    }
    else
    {
        move += bs + s - 1 + a;
        move += (a == 0)? 2:0;
    }
    
    std::cout << move << std::endl;
    return 0;
}