import numpy as np
from numpy import fft

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


def main(N, A):
    f = fft.rfftfreq(N, 1/N)
    C = fft.rfft(A, N)

    fpeak = f[np.argsort(np.abs(C))[-20:]]

    dif = [np.abs(fpeak - freq[i]).min() for i in range(7)]
    ans = -1
    p = 1e12
    for i, d in enumerate(dif):
        if p > d:
            ans = i
            p = d
    print(code[ans])


N = int(input())
A = np.array(input().split(), dtype=np.float64)
main(N, A)