Need help!! Returning a value from a method.

import java.util.Scanner;
public class sum_number
{
	public static void main(String[] args)
	{
		int a,b,c, sum;
		Scanner input = new Scanner(System.in);

		System.out.print("Enter any number:\n");
		a = input.nextInt();

		System.out.print("Enter another number:");
		b = input.nextInt();

		isum(a,b);

		System.out.print("The addtion result of the entered numbers is: " +z);
	}

	public static isum(int a, int b)

	{
		int z;
		z= a+b;
		return z;
	}

}


//Here is the result what I got. Please help me by correcting this code:

C:\Users\Sanjib\Documents\sum_number.java:20: invalid method declaration; return type required
	public static isum(int a, int b)
	              ^
1 error

Tool completed with exit code 1