import java.io.*;
import antlr.collections.AST;

class Main {
	public static void main(String[] args) {
		try {
			ExprLexer lexer = new ExprLexer(new DataInputStream(System.in));
			ExprParser parser = new ExprParser(lexer);

			// set the type of tree node to create; this is default action
			// so it is unnecessary to do it here, but demos capability.
			parser.setASTNodeType("antlr.CommonAST");

			parser.expr();
			antlr.CommonAST ast = (antlr.CommonAST)parser.getAST();
			if (ast != null) {
				System.out.println(ast.toStringList());
			} else {
				System.out.println("null AST");
			}
		} catch(Exception e) {
			System.err.println("exception: "+e);
		}
	}
}