#include <bits/stdc++.h> using namespace std; #define rep(i,n) for(int i=0; i<(int)n; i++) #define repi(i,m,n) for(int i=(int)m; i<=(int)n; i++) #define rrep(i,n) for(int i=(int)n-1; i>=0; i--) #define rrepi(i,m,n) for(int i=(int)n; i>=(int)m; i--) #define all(x) x.begin(),x.end() template <typename T> inline bool chmin(T& a, const T& b) { return a > b ? a = b, true : false; }; template <typename T> inline bool chmax(T& a, const T& b) { return a < b ? a = b, true : false; }; template <typename T> void uniq(std::vector<T> &v){ std::sort(v.begin(),v.end()); v.erase(unique(v.begin(),v.end()),v.end()); } using ll = long long; int main(){ ll n; cin >> n; ll ok = 1,ng = 1e9+1; while(ng - ok > 1){ ll mid = midpoint(ok,ng); if(mid*mid < n) ok = mid; else ng = mid; } cout << ok << endl; return 0; }