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

using namespace std;

int main(){
	long long a,b,c;
	cin >> a >> b >> c;
	long long mid=max(a,c);
	long long mi=min(a,c);
	
	if((b-mid)+1 < (mid-mi)){
		cout << (b-mid)+1 << endl;
	}else{
		cout << mid-mi << endl;
	}
	
	return 0;
}