n = int(input())
A = list(map(int, input().split()))
ma = -33000
mi = 33000

for a in A:
    ma = max(a, ma)
    mi = min(a, mi)

mid = (ma + mi) / 2
thr = (ma + 3 * mid) / 4
thl = (mi + 3 * mid) / 4
cnt = 0
t = 0
for a in A:
    if t == 0 and a > thr:
        cnt += 1
        t = 1
    elif t == 1 and a < thl:
        t = 0

lst = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]
mi = 1000
for l in lst:
    d = abs(l - cnt)
    if d < mi:
        mi = d
        ans = l
print(["C4", "D4", "E4", "F4", "G4", "A4", "B4"][lst.index(ans)])