A computer can make hundreds of calculations in three or four minutes but men can't. It can compose music,draw pictures,play chess,write poetry and sometimes find the right boys for the rights girls. The police use them to get all the information (data) about crimes and traffic. But computer cannot function alone. A computer must have three people;the programmer,the operator and the technician. First the programmer prepares the programs,then the operator presses the right buttons and finally the technicians' services the computer and repairs it when it breaks down. What is the main idea of this paragraph?