Keep getting "Java error: cannot find symbol" when using input.getInt

Question

I am trying to make a basic calculator but I keep getting this error message. I have looked on the internet but nothing seem to help me.

I am not sure whether the program is having trouble or if I have misplaced something in the brackets.

Here are my error messages:

Main.java:9: error: cannot find symbol
        int num1 = input.nextInt;
                        ^
  symbol:   variable nextInt
  location: variable input of type Scanner
Main.java:12: error: cannot find symbol
        int num2 = input.nextInt;
                        ^
  symbol:   variable nextInt
  location: variable input of type Scanner
Main.java:15: error: cannot find symbol
        char operation = input.next().CharAt0();
                                     ^
  symbol:   method CharAt0()
  location: class String
3 errors

Here's my code:

import java.util.Scanner;

import java.util.Scanner;

public class Main {
    static Scanner input = new Scanner(System.in);

    public static void main(String[] args) {

        // Gets both numbers and operator from user

        System.out.println("Enter first number");
        int num1 = input.nextInt;

        System.out.println("Enter second number");
        int num2 = input.nextInt;

        System.out.println("Enter operation (+ - * /)");
        char operation = input.next().CharAt0();
    }

    // Switch case that does calculations   

    static int calculate(num1, num2, operation) {

        switch (operation) {
            case '+':
                System.out.println(num1 + num2);
                break;
            case '-':
                System.out.println(num1 - num2);
                break;
            case '*':
                System.out.println(num1 * num2);
                break;
            case '/':
                System.out.println(num1 / num2);
                break;
            default:
                System.out.println("Not a valid input");
        }
    }
}