#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define int long long
#define all(x) (x).begin(), (x).end()
#define f(i, n) for (int i = 0; i < n; i++)
#define trace(x) cerr << #x << ": " << x << '\n'
int sq(int n)
{
    int x = sqrt(n);
    while (x * x < n)
        x++;
    while (x * x > n)
        x--;
    return x;
}
int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    cin >> n;
    int x = sq(n);
    int ans = 2 * x - 1;
    ans += (x * (x + 1) <= n);
    cout << ans << '\n';
}