자식 프로세스 여러개 생성 후 신호로 종료시킨 뒤, 실행 시간의 합 출력하는 프로그램... 어디에 문제가 있을까요???

#include <unistd.h>
#include <signal.h>
#include <sys/times.h>
#include <stdio.h>
#include <time.h>
 
long int i1=0,i2=0,i3=0,gaptime=0;
long int time1=0,time2=0,time3=0;
long int tick;
int num = 0;
int num1 = 0;
 
static void sig_int(int signo)
{
	printf("child caught\n");
 
	num1++;
	printf("num1 = %d\n",num1);			
 
}
 
int main(void)
{
	int statlot;
	pid_t pid,pid1;
	struct tms buf;
	tick = sysconf(_SC_CLK_TCK);//nano second can be acquired
 
	printf("time = %ld\n",times(&buf)/tick);
 
 
	struct sigaction sig;
	sig.sa_handler = sig_int;
	sigemptyset(&sig.sa_mask);
	sig.sa_flags = 0;
	sigaction(SIGINT,&sig,NULL);
 
 
	pid1 = getpid();
 
 
 
	i1 = times(&buf)/tick;
	if((pid = vfork()) < 0)//for sharing variable between parent and child
		printf("fork error 1\n");
 
	if((pid1 = fork()) < 0)
		printf("fork error\n");
	else if(pid1 == 0)
	{
		sleep(5);
		printf("before kill\n");
		kill(pid,SIGINT);
		printf("after kill\n");
		_exit(0);
	}
	else
		_exit(0);//여기까지 보시면 됩니다.
 
	printf("after pid1 process\n");
 	if(pid == 0)//pid is return value, not child pid
	{
 
 
 
		num++;
		printf("num = %d\n",num);
 
 
		pause();
		time1 = times(&buf)/tick;
		gaptime += (time1 - i1);
		printf("gaptime = %ld\n",gaptime);
 
		_exit(0);
 
	}
 
 
	sleep(5);
 
 
 
 
	i2 = times(&buf)/tick;
	if((pid = vfork()) < 0)
		printf("fork error2\n");
 
	if((pid1 = fork()) < 0)
		printf("fork error\n");
	else if(pid1 == 0)
	{
		sleep(7);
		kill(pid,SIGINT);
 
	}
	else 
		_exit(0);
 
	if(pid == 0)
	{
 
		num++;
		printf("num = %d\n",num);
 
		pause();
		time2 = times(&buf)/tick;
		gaptime += (time2 - i2);
		printf("gaptime = %ld\n",gaptime);
 
		_exit(0);
	}
 
	sleep(7);
	if((pid1 = fork()) < 0)
		printf("fork error\n");
	else if(pid1 == 0)
	{
		sleep(5);
		kill(pid,SIGINT);
		_exit(0);
	}
	else
		_exit(0);
 
 
 
	i3 = times(&buf)/tick;
	if((pid = vfork()) < 0)
		printf("fork error 3\n");
 
	if((pid1 = fork()) < 0)
		printf("fork error\n");
	else if(pid1 == 0)
	{
		sleep(9);
		kill(pid,SIGINT);
		_exit(0);
	}
 
	if(pid == 0)
	{
 
		num++;
		printf("%ld\n", time3);
 
		pause();
		time3 = times(&buf)/tick;
		gaptime += (time3 - i3);
 
		_exit(0);//for not flushing stream
 
	}
 
	sleep(9);
 
	if(num == 3)
	{
		printf("child processes's running sum time = %ld seconds\n", gaptime);
	}
	return 0;
 
}