#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
#define PLL pair<long long, long long>
#define int long long
#define LL long long
 
#define faster {ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);}
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define all(v) v.begin(),v.end()
 
const LL mod = 998244353;
const int N = 1e5 + 10;
 
const LL INF = 1e17 + 1;
const int inf = 1e9 + 1;

int n, k; 
LL p[N], d[N], left[N], right[N], vis[N][2], cyc[N][2];

int cycle(int id, int dir){
    if(~cyc[id][dir]) return cyc[id][dir];
    if(vis[id][dir]) return 1;
    vis[id][dir] = 1;

    int inc = dir; if(!inc) inc = -1;

    for(int i = id + inc; i < n and i >= 0; i += inc){
        int dis = (abs(p[i] - p[id])) % k;
        int td = (d[i] - d[id] + k) % k;
        if(dis == td){
            return cyc[id][dir] = cycle(i, 1 - dir);
        }
    }
    return cyc[id][dir] = 0;
}

void solve(int tc) {
    int n; cin >> n;
    int m = sqrt(n);
    if(m * (m + 1) <= n) m = 2 * m;
    else m = 2 * m - 1;
    cout << m << '\n';
}
 
signed main() {
    faster
    int t = 1;
    // cin >> t;
    for (int tc = 1; tc <= t; tc++) {
        solve(tc);
    }
    return 0;
}