Help to solve Minimum Deletion RD19

Hi there, I am new in this forum, so please help me with your suggestions.. Earlier today I was trying to solve the problem under "Practice>Beginner" named "Minimum Deletion" tag:RD19 I know it's a smart way to solve this by finding GCD of the numbers but I tried something else. The GCD of the numbers suppose to be 1 if all of them are PRIME numbers, so we just wanna know how many numbers are not prime in the given nembers.. So I write the code which is looking fine to me but after submission it says "Wrong answer" I will appreciate if someone help me to find the bug in my code...

//RD19
//Unsolved
#include<stdio.h>
#include<math.h>
int test_case(int ara[], int b);
int main()
{
    int a,b,d,e;
    int i,j;
    int x,y;
    scanf("%d",&a);
    for(j=0;j<a;j++)
    {
        scanf("%d",&b);
        int ara[b];
        for(i=0;i<b;i++)
        {
            scanf("%d",&ara[i]);
        }
            x=test_case(ara,b);
    if(x==1)
    {
        x=-1;
        printf("%d\n",x);
    }
    else
    {
    printf("%d\n",x);
    }
    }
    return 0;
}
int test_case(int ara[], int b)
{
    int i,j,k=0,x=0,y; 
    for(i=0;i<b;i++)
    {
        if(ara[i]==1||ara[i]==2)
        {
            x=0;
        }
        else if(ara[i]%2==0)
        {
            x=1;
        }
        y=sqrt(ara[i]);
        for(j=3;j<=y;j=j+2)
        {
            if(ara[i]%j==0)
            {
                x=1;
            }

        }
        if(x==1)
        {
            k=k+1;
        }
    }
    return k;   
}