public class Exp{
   public static void main(String[] args){
      System.out.println(pow(2,30));
      System.out.println(pow(2.0,30)); //tests
      System.out.println(pow(2.0,-2));
   }

   public static double pow(double base, int exp){
      if(exp < 0) return 1 / pow(base, -exp);
      double ans = 1.0;
      for(;exp > 0;--exp) ans *= base;
      return ans;
   }
}