#include #include #define rep(i,a,b) for(int i=a;i=a;i--) #define all(x) (x).begin(),(x).end() #define pb(x) push_back(x); templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b; const ll mod=998244353; //const ll mod=1e9+7; int dx[4]={1,0,-1,0}; int dy[4]={0,1,0,-1}; const string zton="0123456789"; const string atoz="abcdefghijklmnopqrstuvwxyz"; const ll inf=(1ll<<60); ll gcd(ll a,ll b){ ll r; r=a%b; if(r==0){ return b; } else{ return gcd(b,r); } } typedef pair P; int main(void){ ios::sync_with_stdio(false); cin.tie(nullptr); int eratos[201010]; rep(i,0,201010)eratos[i]=-1; eratos[0]=1; eratos[1]=1; rep(i,2,201010){ if(eratos[i]!=-1)continue; eratos[i]=i; int x=i*2; while(x<=201010){ if(eratos[x]==-1){ eratos[x]=i; } x+=i; } } int N;cin >> N; ll N2[N+1];rep(i,0,N+1)N2[i]=(i*1ll*i); ll ans=0; rep(i,1,N+1){ map cnt; int n_=i; while(n_!=1){ cnt[eratos[n_]]++; n_/=eratos[n_]; } ll m=1; for(P p:cnt){ if(p.second%2==1){ m*=p.first; } } ll n=N/m; auto iter=upper_bound(N2,N2+N+1,n); int id=iter-N2; ans+=id; ans--; } cout << ans << endl; }