#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

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

    int ans = 0;
    if(s == 1){
        ans = a;
    }else if(abs(a - s) <= abs(b - s)){
        ans = abs(a-s) + s;
    }else{
        ans = abs(b - s);
        b = s;
        if(a == 0){
            ans += s + 1;
        }else if(a < b){
            ans += s;
        }else{
            ans += a - b + a;
        }
    }

    cout << ans << endl;
    return 0;
}