#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <math.h>
#include <map>

using namespace std;

int main(){
	vector<int> a(3,0);
	cin >> a[0] >> a[1] >> a[2];
	sort(a.begin(),a.end());
	
	int down_cost=a[2]-a[1]+1;
	int up_cost=a[1]-a[0];
	cout << min(down_cost,up_cost) << endl;
	
	return 0;
}