import numpy as np
from scipy.signal import fftconvolve
N, X = map(int, input().split())
A = np.array(input().split(), dtype=np.int32)
A = np.bincount(A)

F = np.rint(fftconvolve(A, A) + 0.01).astype(np.int32)
if X < len(F):
    print(F[X])
else:
    print(0)