function getRoot() {
var doc = DocumentApp.getActiveDocument();
var header = doc.getHeader() || doc.addHeader();
var name = doc.getName();
var id = doc.getId();
var txt = "Master Folder";
var parents = [];
var folders = DriveApp.getFileById(id).getParents();
while (folders.hasNext()) {
var folder = folders.next();
parents.push(folder.getName());
folders = folder.getParents();
}
parents = parents.reverse();
var pLen = parents.length;
for (i = 0; i < pLen; i++){
txt = txt + "//" + parents[i];
}
var headerPar = header.appendParagraph(txt);
}