program PROG15 (input,output);
	var      invalid_operator : boolean;
	         operator : char;
	         number1, number2, result : real;

	procedure MULTIPLY;
	begin
	         result := number1 * number2
	end;

	procedure DIVIDE;
	begin
	         result := number1 / number2
	end;

	procedure ADD;
	begin
	         result := number1 + number2
	end;

	procedure SUBTRACT;
	begin
	         result := number1 - number2
	end;

	procedure GET_INPUT;
	begin
	         writeln('Enter two numbers and an operator in the format');
	         writeln(' number1 operator number2');
	         readln(number1); readln(operator); readln(number2)
	end;

	begin
	         invalid_operator := FALSE;
	         GET_INPUT;
	         case operator of
	             '*': MULTIPLY;
	             '/': DIVIDE;
	             '+': ADD;
	             '-': SUBTRACT;
	         otherwise invalid_operator := TRUE
	         end;
	         if invalid_operator then
	            writeln('Invalid operator')
	         else
	            writeln(number1:4:2,' ', operator,' ', number2:4:2,' is '
	                    ,result:5:2)
	end.

	{Special changes for Turbo are                           
	         case operator of
	             '*': result := MULTIPLY;
	             '/': result := DIVIDE;
	             '+': result := ADD;
	             '-': result := SUBTRACT;
	         else invalid_operator := TRUE
	         end;                                            }