import numpy as np
N = int(input())
A = list(map(int, input().split())) 
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]
for i in range(1,300):
    if 259*i<=ans<=263*i or ans == 1570:
        print('C4')
        exit()
    elif 292*i<=ans<=295*i:
        print('D4')
        exit()
    elif 325*i<=ans<=329*i:
        print('E4')
        exit()
    elif 345*i<=ans<=351*i:
        print('F4')
        exit()
    elif 388*i<=ans<=399*i:
        print('G4')
        exit()
    elif 432*i<=ans<=441*i:
        print('A4')
        exit()
    elif 484*i<=ans<=496*i:
        print('B4')
        exit()
print('B4')