#include <bits/stdc++.h> using namespace std; #include <atcoder/all> using namespace atcoder; using mint = atcoder::static_modint<998244353>; // // using mint = atcoder::static_modint<1000000007>; using ld = long double; using ll = long long; #define mp(a,b) make_pair(a,b) #define rep(i,s,n) for(int i=s; i<(int)n; i++) const vector<int> dx{1,0,-1,0},dy{0,1,0,-1}; ll floor_sqrt(ll x){ ll l=0; ll r=3000000003; while(r-l>1){ ll m=(l+r)/2; if(m*m<=x)l=m; else r=m; } return l; } int main(){ ll n; cin >> n; cout << floor_sqrt(n); }