#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int H,W,K;
  cin>>H>>W>>K;
  if(H > W) swap(H,W);
  if(K <= H) cout<<K+1<<endl;
  else if(K <= W) cout<<H+1<<endl;
  else if(K <= H+W) cout<<1+H+W-K<<endl;
  else cout<<0<<endl;
}