#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n;
  cin >> n;
  long long int start = 1, end = 1e10;
  while (start < end) {
    long long int mid = (start) + (end - start) / 2;
    if (n / mid > 1)
      start = mid + 1;
    else
      end = mid - 1;
  }
  if (n / start > 1)
    cout << start + 1 << endl;
  else
    cout << start << endl;
  return 0;
}
