#include <bits/stdc++.h>
#define p(s) cout<<(s)<<endl
using namespace std;

int main(){
	int x,y,d;
	cin>>x>>y>>d;
	int ans;
	if(x+y<d) ans=0;
	else if(x>=d&&y>=d) ans=d+1;
	else ans=min(d,x)+1-max(d-y,0);

	p(ans);
	return 0;
}