#include <bits/stdc++.h>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;

int main(){
	ll x, y, z;
	cin >> x >> y >> z;
	ll ans=z;
	if(x<=z) ans--;
	if(y<=z) ans--;
	cout << max(0ll, ans) << endl;
	return 0;
}