const int MAXSIZE = 100;

struct BigNum{
   int digits[MAXSIZE];
   bool sign;
   int length;
};

void read_bignum(BigNum  & a);
void print_bignum(BigNum  a);
void init_bignum(BigNum & a);

int compare_bignum(BigNum a, BigNum b);
void copy_bignum(BigNum source, BigNum & dest);
void swap_bignum(BigNum & a, BigNum & b);

void operate_bignum(char op, BigNum a, BigNum b, BigNum & c) ;
void add_bignum(BigNum a, BigNum b, BigNum & c) ;
void sub_bignum(BigNum a, BigNum b, BigNum & c) ;
void mult_bignum(BigNum a, BigNum b, BigNum & c) ;
void div_bignum(BigNum a, BigNum b, BigNum & c) ;