import numpy as np

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

A = A / 32768
Data = np.abs(np.fft.fft(A))
Freq = np.fft.fftfreq(Data.shape[0], d=1.0/n)

idx = Data.maxarg()
diff = 1000
ans = 0
F = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]
S = ['C4', 'D4', 'E4', 'F4', 'G4', 'A4', 'B4']
for i in range(7):
    d = abs(Freq[idx] - F[i])
    if d < diff:
        diff = d
        ans = S[i]
print(ans)