统一将时间转化为分钟

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        int res = (c * 60 + d) - (a * 60 + b);
        System.out.println(res);
    }
}