Java programs to find the coprimes of a number

// coprimes of any number n are numbers bw 1 and n, which are not divisible by any factors of n
public class Coprimes
{

public static void main(String args[])
{
int sum=0;
int p=0;
int y;
for(int i=18; i<=23; i++)
{
sum=0;
p=0;
int[]a=new int[i/2];
for(int j=2; j<=i/2; j++)
{
if(i%j==0 && IsPrime(j)==true)
a[p++]=j;
}

System.out.println("For "+i+", the co-primes are:");
for(int x=1; x {
for(y=0; y {
if(x%a[y]==0)
break;
}
if(y==p)
{
sum+=x;
System.out.println(x);
}
}
System.out.println("Their sum is "+sum);
System.out.println("");
System.out.println("");
}
}

public static boolean IsPrime(int a)
{
a=Math.abs(a);
for(int i=2; i<=a/2; i++)
if(a%i==0)
return false;
return true;
}
}