#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>





int a[20];
int n,nrp;
int s=0;

void childProc(int readPipe, int writePipe) {

  int i=1, j, sum=0;
  read(readPipe, &i, sizeof(int));
    for(j=i*(n/nrp);j<(i+1)*(n/nrp);j++)
      if(j<n)
	sum=sum+a[j];
  write(writePipe,&sum, sizeof(int));
  exit(1);
}



void parentProc(int readPipe, int writePipe) {
  int rez,j,val;
  for(j=0;j<nrp;j++)
    {
      write(writePipe,&j,sizeof(int));
    }
      for(j=0;j<nrp;j++)
	{
	  read(readPipe, &val, sizeof(int));
	  s+=val;

	}
      wait(2000);
}

int main() {
  int firstPipe[2];
  int secondPipe[2];
  int pid=1,i,j;

  printf("n=");scanf("%d",&n);

  for(i=0;i<n;i++)
    {
      printf("a[%d]=",i);
      scanf("%d",&a[i]);
    }
  nrp=4;
  if (pipe(firstPipe)) {
    printf("Nu am putut crea conducta!\n");
    exit(-1);
  }
  if (pipe(secondPipe)) {
    printf("Nu am putut crea conducta!\n");
    exit(-1);
  }

  for(j=0;j<nrp;j++)
    {
      pid = fork();
      if (pid) {
	if (pid == -1) {
	  printf("Nu am reusit crearea procesului copil.\n");
	  exit(-1);
	}

      } else {
	childProc(firstPipe[0], secondPipe[1]);
      }
    }
  parentProc(secondPipe[0], firstPipe[1]);
  printf("suma: %d\n",s);

  wait(2000);
  printf("Procesul principal gata!\n");
}