new to recursion, getting StackOverflow. Help!

I am writing a divide and conquer recursive function to find minimum element in array. But I am getting java.lang.StackOverflowError . Here is my code. Thanks in advance.

import java.util.Scanner;

public class dynamic {

    public static void main(String arg[])
    {   int i=0;
        Scanner s=new Scanner(System.in);
        int num[]=new int[8];
        while(i<8)
        {
            num[i]=s.nextInt();
            i++;
        }

        int b=findmin(num);
        System.out.println(b);
    }

    public static int findmin(int num[])
    {
        if(num.length==0)return 0;

        return findmin(num,0,num.length-1);
    }

    public static int findmin(int num[],int first,int last)
    {   
        if(first==last )return num[first];
        if(first+1==last)return Math.min(num[first],num[last]);

        if(findmin(num,(last/2)+1,last)>findmin(num,first,last/2)) return findmin(num,first,last/2);
        else return findmin(num,(last/2)+1,last);



    }

}