Problem:
Score : 500 points

Problem Statement

Consider sequences \{A_1,...,A_N\} of length N consisting of integers between 1 and K (inclusive).

There are K^N such sequences. Find the sum of \gcd(A_1, ..., A_N) over all of them.

Since this sum can be enormous, print the value modulo (10^9+7).

Here \gcd(A_1, ..., A_N) denotes the greatest common divisor of A_1, ..., A_N.

Constraints

2 \leq N \leq 10^5

1 \leq K \leq 10^5

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the sum of \gcd(A_1, ..., A_N) over all K^N sequences, modulo (10^9+7).

Sample Input 1

3 2

Sample Output 1

9

\gcd(1,1,1)+\gcd(1,1,2)+\gcd(1,2,1)+\gcd(1,2,2)
+\gcd(2,1,1)+\gcd(2,1,2)+\gcd(2,2,1)+\gcd(2,2,2)
=1+1+1+1+1+1+1+2=9

Thus, the answer is 9.

Sample Input 2

3 200

Sample Output 2

10813692

Sample Input 3

100000 100000

Sample Output 3

742202979

Be sure to print the sum modulo (10^9+7).

Solution in Python (3.8.2) (judge verdict: Accepted)

import sys

sys.setrecursionlimit(10 ** 8)
ni = lambda: int(sys.stdin.readline())
nm = lambda: map(int, sys.stdin.readline().split())
nl = lambda: list(nm())
ns = lambda: sys.stdin.readline().rstrip()

MOD = 10 ** 9 + 7
N, K = nm()


def solve():
    ans = 0
    tbl = [0] * (K + 1)
    for i in range(K, 0, -1):
        m = K // i
        p = pow(m, N, MOD)

        j = 2
        while j * i <= K:
            p += MOD - tbl[j * i] % MOD
            p %= MOD
            j += 1
        tbl[i] = p

        ans += i * p % MOD
        ans %= MOD
    return ans


print(solve())