#include <iostream>
 
const int NMIN = 10000000, NMAX = 100000000;
char notprime[NMAX]; // Mark the composite numbers
 
int main() {
  // Sieve all primes
  // We only need to sieve up to sqrt(MAXN)
  for (int i = 2; i*i <= NMAX; ++i) {
    if (notprime[i]) continue;
 
    // Mark all multiples starting with i^2
    for (int j = i*i; j <= NMAX; j += i) notprime [j] = 1;
  }
 
  // Count primes from NMIN to NMAX
  int cntprimes = 0;
  for (int i = NMIN; i <= NMAX; ++i) {
    if (!notprime[i]) ++cntprimes;
  }
 
  std::cout << cntprimes << "\n";
  return 0;
}

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