#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int t = 1, a, b, c, ans = 0;
  while (t--) {
    cin >> a >> b >> c;
    for (int i = 0; i <= a; i++)
      for (int j = 0; j <= b; j++)
        if (i + j == c) ans++;
    cout << ans;
  }
  return 0;
}
