Минимум 4 чисел

Main.java

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println(min(in.nextInt(), in.nextInt(), in.nextInt(), in.nextInt()));
    }

    static int min(int a, int b, int c, int d) {
        return Math.min(a, Math.min(b, Math.min(c, d)));
    }

}