func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<pair<long long, int> > H[1000007];   long long n, val[1000005], ans, cnt[1000005];   int S[1000005];   int m, up[1000005], p[1000005], len, b[1000005], mp[1000005];   void prepare() {     int i, j;     b[1] = 1;     for (i = 2; i < 1000005; i++) {       if (!b[i]) p[++len] = i;       for (j = 1; j <= len; j++) {         if (1LL * i * p[j] >= 1000005) break;         b[1LL * i * p[j]] = 1;         if (i % p[j] == 0) break;       }     }     for (i = 1; i < 1000005; i++) S[i] = S[i - 1] + (!b[i]);     for (i = 1; i <= len; i++) mp[p[i]] = i;     for (i = 1000005 - 1; i >= 1; i--) mp[i] = mp[i] ? mp[i] : mp[i + 1];   }   int SQRT(long long n) {     int p = (int)(sqrt(n));     while (1LL * p * p <= n) p++;     return p;   }   long long find(long long x, int t) {     int i, u = x % 1000007, p;     for (i = 0; i < H[u].size(); i++)       if (H[u][i].first == x) break;     p = H[u][i].second;     return t > up[p] ? cnt[p] + up[p] - t : cnt[p];   }   long long Pi(int t) { return cnt[t] + up[t] - 1; }   void update(int t) {     long long i, x = val[t], l = n / (x + 1) + 1, r = n / x;     r = min(r, (long long)(sqrt(n)));     for (i = l; i <= r; i++)       if (!b[i]) ans += Pi(t) - S[i];   }   int main() {     long long i, j = 1, q = 1;     long long x = 0;     cin >> n;     prepare(), m = 1;     for (i = 1; 1LL * p[i] * p[i] * p[i] <= n; i++) ans++;     for (i = 1; i <= n; i = n / (val[m++]) + 1) val[m] = n / i;     m--, sort(val + 1, val + m + 1);     for (i = 1; i <= m; i++)       H[val[i] % 1000007].push_back(pair<long long, int>(val[i], i));     for (i = 1; i <= m; i++) up[i] = mp[SQRT(val[i])];     for (i = 1; i <= up[m]; i++) {       for (j = m; j >= q; j--) {         if (i != 1) {           x = find(val[j] / p[i - 1], i - 1);           cnt[j] = cnt[j] - x - 1;         } else           cnt[j] = val[j] - 1;       }       while (q <= m && i == up[q]) update(q++);     }     cout << ans;     return 0;   }   