import numpy as np
N = int(input())
A = list(map(int, input().split())) 

# 高速フーリエ変換(FFT)
F = np.fft.fft(A)
# 振幅スペクトルを計算
amplitude = np.abs(F)
F_amplitude = amplitude / N * 2
F_amplitude[0] = F_amplitude[0] / 2
v = 0
ans = 0
for i in range(len(F_amplitude)):
	if v<F_amplitude[i]:
		ans=i
		v=F_amplitude[i]
if 1569<=ans<=1571:
    print('C4')
elif 292<=ans<=295:
    print('D4')
elif 326<=ans<=328:
    print('E4')
elif 348<=ans<=350:
    print('F4')
elif 391<=ans<=395:
    print('G4')
elif 435<=ans<=437:
    print('A4')
else:
    print('B4')