#include <stdio.h>

extern double zbir(double, double);
extern double proizvod(double, double);
extern double f(double, double);
extern double g(double);

int main() {
  printf("%g\n", zbir(1,2));
  printf("%g\n", proizvod(1,2));
  printf("%g\n", f(1,2));
  printf("%g\n", g(2));
  return 0;
}