1  import java.util.Scanner;
  2  
  3  public class ImprovedFibonacci {
  4    /** Main method */
  5    public static void main(String[] args) {
  6      // Create a Scanner
  7      Scanner input = new Scanner(System.in);
  8      System.out.print("Enter an index for the Fibonacci number: ");
  9      int index = input.nextInt();
 10      
 11      // Find and display the Fibonacci number
 12      System.out.println(
 13        "Fibonacci number at index " + index + " is " + fib(index));
 14    }
 15    
 16    /** The method for finding the Fibonacci number */
 17    public static long fib(long n) {   
 18      long f0 = 0; // For fib(0)
 19      long f1 = 1; // For fib(1)
 20      long f2 = 1; // For fib(2)
 21      
 22      if (n == 0) 
 23        return f0;
 24      else if (n == 1) 
 25        return f1;
 26      else if (n == 2) 
 27        return f2;
 28  
 29      for (int i = 3; i <= n; i++) {
 30        f0 = f1;
 31        f1 = f2;
 32        f2 = f0 + f1;
 33      }
 34      
 35      return f2;
 36    }
 37  }