#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

static const double EPS = 1e-8;
static const double PI = 4.0 * atan(1.0);
static const double PI2 = 8.0 * atan(1.0);

#define REP(i,n)	for(int i=0;i<(int)n;++i)
#define ALL(c)		(c).begin(),(c).end()
#define CLEAR(v)	memset(v,0,sizeof(v))
#define MP(a,b)		make_pair((a),(b))
#define ABS(a)		((a)>0?(a):-(a))
#define FOR(i,s,n)	for(int i=s;i<(int)n;++i)

int main(int argc, char **argv) {
	int A, B, S;
	cin >> A >> B >> S;
	if (S == 1) {
		if (A == 0) cout << 2 << endl;
		else cout << A << endl;
	}
	else if (abs(A - S) <= abs(B - S)) {
		if (A > S) cout << A << endl;
		else cout << (S + S - A) << endl;
	}
	else if (abs(A - S) <= S - 1) {
		cout << (abs(B - S) + A + abs(A - S)) << endl;
	}
	else {
		if (B > S) cout << (B - 1 + A) << endl;
		else cout << (S - 1 + S - B + A) << endl;
	}
	return 0;
}