#include <16F877A.h>
#device ADC=10
#use delay(crystal=20000000)
#use FIXED_IO( C_outputs=PIN_C3,PIN_C2,PIN_C1,PIN_C0 )
#use FIXED_IO( D_outputs=PIN_D1,PIN_D0 )
#define a   PIN_C0
#define b   PIN_C1
#define c   PIN_C2
#define d   PIN_C3
#define f1   PIN_D0
#define f2   PIN_D1
#define SW  PIN_B0