#include<bits/stdc++.h>
#define ll long long
#define int long long
using namespace std;
void solve()
{
   int n; cin>>n;
   int ans=0;
   if(n==1){
    cout<<1<<endl;return;
   }
   for(int i=1;i<n;i++)
   {
        if(i*i>n) break;
        if(i*i<=n)ans++;
        if(i*(i+1)<=n)ans++;

   }
   cout<<ans<<endl;
}
main()
{
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    solve();
    return 0;
}