int function ( ) { return - 1 ; }
task 7 : advanced calculator history commands cumulativesum computes the sum over the result of each equation in our history . concode_field_sep PlaceHolder placeHolder concode_field_sep int add concode_elem_sep void printHistory concode_elem_sep void printAllHistory concode_elem_sep void clearHistory concode_elem_sep void undoEquation concode_elem_sep int multiply concode_elem_sep void saveEquation concode_elem_sep int cumulativeProduct