import numpy as np
import bisect

n = int(input())
a = list(map(int, input().split(' ')))

f = np.fft.fft(a)
freq = np.fft.fftfreq(n, 1/n)
amp = np.abs(f/(n/2))


l = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]
max = 0
maxval = 0.0
for i in range(len(l)):
    idx = bisect.bisect_left(freq[0:len(freq)//2], l[i])
    buf = amp[idx]

    if maxval < buf:
        max = i
        maxval = buf

if max == 0:
    print("C4")
if max == 1:
    print("D4")
if max == 2:
    print("E4")
if max == 3:
    print("F4")
if max == 4:
    print("G4")
if max == 5:
    print("A4")
if max == 6:
    print("B4")