#include <bits/stdc++.h>
//#include <rng_58>
//#include <chokudai>
//#include <tourist>
using namespace std;

// Macro and Macro Functions
#define rep(a, b) for(int a = 0; a < b; ++a)
#define REP(a, b, c) for(int a = b; a < c; ++a)
#define drep(a, b, c) for(int a=0,b=0;b<c?:(b=0,++a<c);++b)
#define int long long
#define between(n,_min,_max) if(_min<=n&&n<=_max)
#define SORT(a) sort(ALL(a))
#define RSORT(a) sort(RALL(a))
#define REVERSE(a) reverse(ALL(a))
#define MOD 1000000007
#define Beg(a) (a).begin()
#define End(a) (a).end()
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define ALLIN(a) rep(nanika,a.size()) cin>>a[nanika]
#define ALLINDE(a) rep(kyawa,a.size()){cin>>a[kyawa]; --a[kyawa];}
#define YN(a) do{if(a) cout<<"YES"; else cout<<"NO";}while(0)
#define Yn(a) do{if(a) cout<<"Yes"; else cout<<"No";}while(0)
#define yn(a) do{if(a) cout<<"yes"; else cout<<"no";}while(0)
#define spa " "
#define dspa "  "
#define ctoi(c) (c)-'0'
#define altoi(a) (a)-'a'
#define fi first
#define se second
#define dvec(type,name,row,column,value) vector<vector<type>> name(row,vector<type>(column,value))
 
// List of using
using ll   = signed long long;
using ull  = unsigned long long;
using pint = pair<int,  int>;
using pong = pair<long, long>;
using tint = tuple<int,  int,  int>;
using tong = tuple<long, long, long>;
using vint = vector<int>;
using vll  = vector<long long>;
using vbol = vector<bool>;
using vstr = vector<string>;
using vull = vector<unsigned long long>;
using dvin = vector<vector<int>>;
using dvbo = vector<vector<bool>>;
using mint = map<int,int>;
 
// Common Variable
bool DEBUG=false;
long long INF=2000000000;

void print(){
  cout<<'\n';
}

template<class HEAD,class... TAIL>
void print(HEAD&& head,TAIL&&... tail){
  cout<<head<<spa;
  print(forward<TAIL>(tail)...);
}

void scan(){}

template<class HEAD,class... TAIL>
void scan(HEAD&& head,TAIL&&... tail){
  cin>>head;
  scan(forward<TAIL>(tail)...);
}

template<typename t>
void print(vector<t> &v){
  rep(i,v.size()){
    cout<<v[i]<<spa;
  }
  cout<<endl;
}

template<typename t, typename u>
void print(vector<pair<t,u>> &v){
  rep(i,v.size()){
    cout<<i<<" : "<<v[i].first<<" "<<v[i].second<<endl;
  }
}

int RepeatSquaring(int N, int P, int M){
  if(P==0) return 1;
  if(P%2==0){
    int t = RepeatSquaring(N, P/2, M);
    return t*t % M;
  }
  return N * RepeatSquaring(N, P-1, M);
}
//--------------------------------
// Template Place
//--------------------------------
// int dx[]={ 1, 0,-1, 0};
// int dy[]={ 0,-1, 0, 1};

signed main(){
  int x,y,d; cin>>x>>y>>d;
  int xa,xb;
  if(d>x+y){
    cout<<0<<endl;
  }
  else{
    xa=max((int)0,d-y),xb=min(d,x);
    cout<<xb-xa+1<<endl;
  }
}