#include <bits/stdc++.h>
using namespace std;
int n, b, g, ans;
int main() {
  scanf("%d%d%d", &b, &g, &n);
  for (register int i = 0; i <= n; ++i) {
    register int a = i, f = n - i;
    if (a <= b && f <= g) ++ans;
  }
  printf("%d\n", ans);
  return 0;
}
