import numpy as np
import sys

n = int(sys.stdin.buffer.readline())
assert n == 44100
a = np.array(sys.stdin.buffer.readline().split(), dtype=np.float64)
amp = np.abs(np.fft.fft(a))
afreq = 200 + np.argmax(amp[200:500])

labels = ["C4", "D4", "E4", "F4", "G4", "A4", "B4"]
freqs = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]

ae = np.inf
al = ""
for i in range(7):
    err = np.abs(afreq - freqs[i])
    if err < ae:
        ae = err
        al = labels[i]
print(al)