Adjacent package does not exist

Question

I have a public class Mountain in Four\ Seasons\ Lab/things/Mountain.java and try to import the class public class Triangle, which is in Four\ Seasons\ Lab/shapes/Triangle.java, using import shapes.Triangle (note: import shapes.* also doesn't work). For some reason, this keeps throwing package shapes does not exist, as well as cannot find symbol on any time I try to use the Triangle class. How do I fix this?

Mountain.java

package things;

import shapes.Triangle;

import java.awt.Graphics;
import java.awt.Color;

public class Mountain {
    private Triangle body;

    public Mountain(int x, int y, int dx, int dy) {
        this.body = new Triangle(
            x, y + dy,
            x + dx/2, y,
            x + dx, y + dy
        );
    }

    public void draw(Graphics g) {
        body.draw(g);
    }
}

Triangle.java

package shapes;

import java.awt.Graphics;
import java.awt.Color;

public class Triangle {
    private Color color;
    private int[] pointA;
    private int[] pointB;
    private int[] pointC;
    
    public Triangle(Color color, int aX, int aY, int bX, int bY, int cX, int cY) {
        this.color = color;
        this.pointA = new int[] {aX, aY};
        this.pointB = new int[] {bX, bY};
        this.pointC = new int[] {cX, cY};
    }
    // more code
}

File Tree

Screenshot of Mountain.java

Note:

1. Runner will run Scenery, which will run Mountain
2. The program must run in terminal through:

(in "Four Seasons Lab" directory)
$ javac *.java
$ java Runner

(it is shared via a .zip file containing only the .java files)

Answer 1

The problem wasn't with my IDE or my code or anything. I am using Atom as an IDE and linter-javac package as a linter. This is just a problem with the linter.