Problem:
Power

For given integers m and n, compute mn (mod 1,000,000,007). Here, A (mod M) is the remainder when A is divided by M.

Input

m n

Two integers m and n are given in a line.

Output

Print mn (mod 1,000,000,007) in a line.

Constraints

1 ≤ m ≤ 100

1 ≤ n ≤ 109

Sample Input 1

2 3

Sample Output 1

8

Sample Input 2

5 8

Sample Output 2

390625

Solution in C# (judge verdict: Accepted)

using System;

public class Hello
{
    public const int MD = 1000000007;
    public static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var m = int.Parse(line[0]);
        var n = int.Parse(line[1]);
        Console.WriteLine(power(m, n));
    }
    public static long power(int m, int n)
    {
        var w = (int)(Math.Log10(n) / Math.Log10(2)) + 1;
        var a = new long[w];
        a[0] = m;
        for (int i = 1; i < w; i++)
            a[i] = (a[i - 1] * a[i - 1]) % MD;
        var ret = 1L;
        for (int i = 0; i < w; i++)
            if (((n >> i) & 1) == 1) { ret *= a[i]; ret %= MD; }
        return ret;
    }
}