#include <16f84.h> 
#fuses xt,NOWDT 
#use delay(clock=4000000) 
#define GREEN_LED PIN_b1 
main() { 
while(pin_b0) { 
output_low(GREEN_LED); 
delay_ms(1000); 
output_high(GREEN_LED); 
delay_ms(1000); 
} 
}