import numpy as np

n = int(input())
A = np.array(list(map(np.float32, input().split())))

A = A / 32768.0
Data = np.fft.fft(A)
Freq = np.fft.fftfreq(Data.shape[0], d=1/n)
Data[(Freq < 250)] = 0.0
Data[(Freq > 500)] = 0.0
idx = np.argmax(Data)
dif = 1000
ans = ''
F = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]
S = ['C4', 'D4', 'E4', 'F4', 'G4', 'A4', 'B4']
p = 1
for i in range(7):
    d = abs(Freq[idx] - F[i])
    if d < dif:
        dif = d
        ans = S[i]
print(ans)