#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<pthread.h>

void *thread_function(void *arg);

 int i,j;

 int main() {

 pthread_t a_thread;  //thread declaration  

 pthread_create(&a_thread, NULL, thread_function, NULL); 

//thread is created

 pthread_join(a_thread, NULL); //process waits for thread to finish . //Comment this line to see the difference

 printf("Inside Main Program\n");

 for(j=20;j<25;j++)

 {

 printf("%d\n",j);

 sleep(1);

 }

 }

void *thread_function(void *arg) {    

// the work to be done by the thread is defined in this function

 printf("Inside Thread\n");

 for(i=0;i<5;i++)

 {

 printf("%d\n",i);

 sleep(1);

 }

 }