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| #include <bits/stdc++.h>
#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
struct PairHash {inline std::size_t operator()(const std::pair<int,int> & v) const {return v.first*31+v.second;}};
#define MAX_N 797979
#define INF 987654321
#define EPS 1e-9
#define ll long long
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vall3 vector<array<ll,3>>
#define all3 array<ll,3>
#define all5 array<ll,5>
#define vall5 vector<all5>
#define vll vector<ll>
#define vi vector<int>
#define vs vector<string>
#define usll unordered_set<ll>
#define uspll unordered_set<pll, PairHash>
#define vvs vector<vs>
#define vvll vector<vll>
#define all(a) begin(a), end(a)
#define rall(a) rbegin(a), rend(a)
using namespace std;
bool sieve[MAX_N];
ll solve(ll n) {
memset(sieve, true, sizeof sieve);
sieve[0] = sieve[1] = false;
vll s;
for(ll i = 2; i < MAX_N; i++) {
if(!sieve[i]) continue;
s.push_back(i);
for(ll j = i * i; j < MAX_N; j += i)
sieve[j] = false;
}
ll res = 0;
for(ll i = 0; pow(s[i],4) < n and i < s.size(); i++) {
auto j = lower_bound(all(s), pow(1.0 * n / s[i], 1.0/3.0)) - begin(s);
if(s[i] * s[j] * s[j] * s[j] > n) j--;
res += max(0ll, j - i);
}
return res;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
ll tc = 1;
for(ll i = 1; i <= tc; i++) {
ll n;
cin>>n;
cout<<solve(n)<<endl;
}
return 0;
}
|
