#include <stdio.h>
#ifdef _OPENMP 
#include<omp.h> 
#endif

int main(int argc, char* argv[])
{

#ifdef _OPENMP
int iam;
#pragma omp parallel
    { /* the parallel block starts here */
        iam=omp_get_thread_num();
#pragma omp critical
        printf("Hello from %d\n",iam);

    } /* the parallel block ends here */

#else
        printf("Hello, this is a serial program.\n");
#endif

    return 0;
}