#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
using P = pair<int, int>;
using vi = vector<int>;
using vl = vector<ll>;
using vll = vector<vl>;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
const ll INF = 1LL << 60;
const double pi = acos(-1);
ll mod = 1000000007;

ll x[200005],y[200005],z[200005],w[200005];

int main() {
    ll x,y,d; cin >> x >> y >> d;
    ll i,j,cnt = 0;
    if(x + y >= d) {
        for(i = d;i >= 0;--i){
            j = d - i;
            if(i <= x && j <= y) cnt++;
            else continue;
        }
    }
    cout << cnt << endl;
    return 0;
}