#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, n, sum = 0, maxi, mini, start, end;
  ;
  cin >> a >> b >> n;
  mini = min(a, b);
  maxi = max(a, b);
  if (n <= min(a, b)) {
    cout << n + 1;
  } else {
    if (mini + maxi >= n) {
      int k = n - maxi;
      if (k < 0) {
        k = 0;
      }
      sum = mini - k + 1;
    }
    cout << sum;
  }
  return 0;
}
