"0";
"-3";
"20"  +  "15";
"20" -  "3" * ("4" - "2");
"1" + "2" + "3" + "5" + "6";
"1" * "2" * "3" * "4" * "5";
("1" + "2") +"3" * "5" + ("10"-"2");
"20" * "-3";
("100" - ("10"-"4"*("6"-"3")));
("15" - "4") * "9" * ("103" - "78") - "45";
