# https://qiita.com/kaityo256/items/64a54bb2e2c477cc6fa1

import numpy as np
from math import sqrt, pi, exp
import matplotlib.pyplot as plt

N = int(input())
y = list(map(int, input().split()))
fk = np.fft.fft(y)
fk2 = [abs(x) for x in fk]
fk2 = fk2[:1000]

"""
plt.plot(y)
plt.show()
"""

#plt.plot(fk2)
#plt.show()

i = fk2.index(max(fk2))
#print(i)

hz = 44100 / i
l = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]
l2 = ["C4", "D4", "E4", "F4", "G4", "A4", "B4"]
l3 = []
for i in range(len(l)):
  shuki = int(l[i] + 0.5)
  l3.append(fk2[shuki])

#print(l3)
ans = l3.index(max(l3))
print(l2[ans])