#include <stdio.h>
      int checkPrime(int n);
      int main() {
        int n, i, flag = 0;
        printf("Enter a positive integer: ");
        scanf("%d", &n);
        for (i = 2; i <= n / 2; ++i) {
          // condition for i to be a prime number
          if (checkPrime(i) == 1) {
            // condition for n-i to be a prime number
            if (checkPrime(n - i) == 1) {
              printf("%d = %d + %d\n", n, i, n - i);
              flag = 1;
            }
          }
        }
        if (flag == 0)
          printf("%d cannot be expressed as the sum of two prime numbers.", n);
        return 0;
      }
      // function to check prime number
      int checkPrime(int n) {
        int i, isPrime = 1;
        // 0 and 1 are not prime numbers
        if (n == 0 || n == 1) {
          isPrime = 0;
        }
        else {
          for(i = 2; i <= n/2; ++i) {
            if(n % i == 0) {
              isPrime = 0;
              break;
            }
          }
        }
        return isPrime;
      }
      
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