Removing zeros + positive and negative arrays

#include "StdAfx.h"
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>


int main()
{
int *a, *b;
int i, n, j = 0, s = 0;

printf("Enter the size : ");
scanf_s("%d", &n);
a = (int*)malloc(n * sizeof(int));

for (i = 0; i < n; i++)
{
printf("a[%d] = ", i);
scanf_s("%d", &a[i]);
}

for (i = 0; i < n; i++)
{
if (a[i] != 0) {
a[j] = a[i];
j++;
}
}
a = (int*)realloc(a, j * sizeof(int));

b = (int*)malloc(j * sizeof(int));
for (i = 0; i < j; i++) {
if (a[i] < 0) {
b[s] = a[i];
s++;
}
}
b = (int*)realloc(b, s * sizeof(int));

n = 0;
for (i = 0; i < j; i++){
if (a[i] > 0){
a[n] = a[i];
n++;
}
}
a = (int*)realloc(a, n * sizeof(int));

printf("Положительные\n");
for (i = 0; i < n; i++){
printf("a[%d] = %d ", i, a[i]);
}
printf("\nОтрицательные\n");
for (i = 0; i < s; i++){
printf("b[%d] = %d ", i, b[i]);
}
free(a);
free(b);
return 0;
}