func_code_string: #include <bits/stdc++.h>   using namespace std;   void segmentedSieve(long long L, long long R) {     long long lim = sqrt(R);     vector<bool> mark(lim + 1, false);     vector<long long> primes;     for (long long i = 2; i <= lim; ++i) {       if (!mark[i]) {         primes.emplace_back(i);         for (long long j = i * i; j <= lim; j += i) mark[j] = true;       }     }     int buenos = 0;     long long len = ceil(sqrt(R - L + 1));     for (long long bloques = 0; bloques < len; ++bloques) {       long long l = L + len * bloques + 1;       if (bloques == 0) l = L;       long long r = min(R, L + len * (bloques + 1));       if (l > r) break;       vector<bool> isPrime(r - l + 1, true);       for (long long i : primes)         for (long long j = max(i * i, (l + i - 1) / i * i); j <= r; j += i)           isPrime[j - l] = false;       if (l == 1) isPrime[0] = false;       for (long long i = l; i <= r; ++i) {         if (i == 2 || (isPrime[i - l] && i % 4 == 1)) {           buenos++;         }       }     }     cout << buenos <<   n ;     return;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     cout << setprecision(20) << fixed;     long long l, r;     cin >> l >> r;     segmentedSieve(l, r);   }   