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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int main() {
  5.  
  6. int i, n;
  7. bool is_prime = true;
  8.  
  9. cout << "Enter a positive integer: ";
  10. cin >> n;
  11.  
  12. // 0 and 1 are not prime numbers
  13. if (n == 0 || n == 1) {
  14. is_prime = false;
  15. }
  16.  
  17. // loop to check if n is prime
  18. for (i = 2; i <= n/2; ++i) {
  19. if (n % i == 0) {
  20. is_prime = false;
  21. break;
  22. }
  23. }
  24.  
  25. if (is_prime)
  26. cout << n << " is a prime number";
  27. else
  28. cout << n << " is not a prime number";
  29.  
  30. return 0;
  31. }
  32.  
Success #stdin #stdout 0.01s 5292KB
stdin
1111111
stdout
Enter a positive integer: 1111111 is not a prime number