function setProject() {
    app.beginUndoGroup("setProject");

    var mainFolder = app.project.items.addFolder("comp");
    app.project.items.addFolder("precomp");

    var subFolder= app.project.items.addFolder("sourceimage");
    subFolder.items.addFolder("picture"); 
    subFolder.items.addFolder("solid"); 
    subFolder.items.addFolder("bgm");
    subFolder.items.addFolder("voice"); 
    subFolder.items.addFolder("se"); 

    var comp1 = mainFolder.items.addComp("master", 1280, 720, 1.0, 3.0, 30);
    app.project.items[2].openInViewer();
    app.endUndoGroup();
}
setProject();