#include <AT89X51.H>

sbit K1=P3^0;

sbit L1=P1^0;

void main(void)

{

  while(1)

    {

      if(K1==0)

        {

          L1=0;                 //灯亮

        }

        else

          {

            L1=1;             //灯灭

          }

    }

}