#include <iostream>
#include <omp.h>
#include <cmath>
 
using namespace std;
 
bool isPrime(int number) {
    if (number <= 1) return false;
    if (number == 2) return true;
    if (number % 2 == 0) return false;
    for (int i = 3; i <= sqrt(number); i += 2) {
        if (number % i == 0) return false;
    }
    return true;
}
 
int main() {
    int I, N;
    cout << "Enter the starting number (I): ";
    cin >> I;
    cout << "Enter the ending number (N): ";
    cin >> N;
 
    int prime_count = 0;
 
    #pragma omp parallel for reduction(+:prime_count)
    for (int i = I; i <= N; ++i) {
        if (isPrime(i)) {
            prime_count++;
        }
    }
 
    cout << "The number of prime numbers between " << I << " and " << N << " is: " << prime_count << endl;
 
    return 0;
}

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