#include<bits/stdc++.h>
using namespace std;
using ll = long long;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll x, y, d;
    cin >> x >> y >> d;

    if(x+y==d){
        p(1);
        return 0;
    }

    if(x+y<d){
        p(0);
        return 0;
    }

    ll ans = d+1;
    ll cut;

    cut = d - x;
    if(cut>0) ans -= cut;

    cut = d - y;
    if(cut>0) ans -= cut;
    
    p(ans);
    return 0;
}