#pragma region header

#include <immintrin.h>
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfenv>
#include <cfloat>
#include <chrono>
#include <cinttypes>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdarg>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <streambuf>
#include <string>
#include <tuple>
#include <type_traits>
#include <typeinfo>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
struct Init{Init(){std::cin.tie(0); ios::sync_with_stdio(false); cout << setprecision(20) << fixed;}} init;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define all(x) begin((x)), end((x))
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define uq(v) v.erase(unique(begin(v), end(v)), end(v))
template<class T> using pq = priority_queue<T>;
template<class T> using pq_g = priority_queue<T, vector<T>, greater<T>>;
template<class T> bool chmax(T &a, const T &b){if(a < b){a = b; return 1; } return 0;}
template<class T> bool chmin(T &a, const T &b){if(a > b){a = b; return 1; } return 0;}
constexpr ll INF = 2e18;
constexpr int inf = 1e9;
constexpr ld eps = 1e-15;
constexpr int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr int dy[8] = {0, 1 ,0, -1, 1, -1, 1, -1};



#pragma endregion header

int main(){
    ll N; cin >> N;
    ll ok = 0, ng = 1e9 + 1;
    while(ng  - ok > 1){
        ll mid = (ok + ng) / 2;
        if(mid * mid <= N) ok = mid;
        else ng = mid;
    }
    cout << ok << "\n";
}