✅Passcode (Contest)

Passcode easy Time Limit: 2 sec Memory Limit: 128000 kB

Problem Statement :

Sara is trying to open a lock for that she needs a passcode. Sara knows that the passcode contains N digits in it and the digits at even indices(0- indexing) are even and the digits at odd indices are {2, 3, 5, 7}. Now Sara wants to know how many different passcodes are possible so that she can open her lock. Input The input contains a single integer N.

Constraints:- 1 <= N <= 10^15 Output Print the number of possible passcodes.

Note:- Since the answer can be quite large so print your ans modulo 10^9+7. Example Sample Input:- 1

Sample Output:- 5

Explanation:- Possible answer:- 0,2,4,6,8

Sample Input:- 4

Sample Output:- 400

link:https://my.newtonschool.co/playground/code/p8gmekkrs2xn/

```java
import java.io.*; // for handling input/output
import java.util.*; // contains Collections framework

// don't change the name of this class
// you can add inner classes if needed
class Main {
    public static void main (String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long mod = 1000000007;
        long ans =1;
        if(n==1)
        {
            ans =5;
        }else if(n%2==0){
            ans = (pow(5,n/2,mod)*pow(4,n/2,mod))%mod;
        }else{
            ans = (pow(5,(n/2)+1,mod)*pow(4,n/2,mod))%mod;
        }
        System.out.println(ans);
    }
        // Your code here
        static long pow(long a, long b, long mod){
            if(b==1)
            return a;
            long ans = pow(a,b/2,mod);
            if(b%2 ==0){
                return (ans*ans)%mod;
            }else{
                return (((a*ans)%mod)*ans)%mod;
            }
        }
       
    
}
```