#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>

#define ll long long

using namespace std;

int main(){

   int x,y,d;
   cin>>x>>y>>d;
   int ans=d+1;
   if(d>x) ans-=(d-x);
   if(d>y) ans-=(d-y);
   ans=max(ans,0);
   cout<<ans<<endl; 

   return 0;
}