from bisect import bisect_left
n = int(input())
a = list(map(int, input().split()))
r = sorted(a)[-500]
s = sorted(a)[500]
p = []
q = []
for i, v in enumerate(a):
    if v > r and (not p or p[-1] < i-50): p.append(i)
    if v < s and (not q or q[-1] < i-50): q.append(i)
d = [p[i+1]-p[i] for i in range(len(p)-1)]
e = [q[i+1]-q[i] for i in range(len(q)-1)]
l = len(d)//3
m = len(e)//3
c = n/max(sum(sorted(d)[l:2*l])/l, sum(sorted(e)[m:2*m])/m)
h = ["C4", "D4", "E4", "F4", "G4", "A4", "B4"]
f = [261.6, 294.3, 327.0, 348.8, 392.4, 436.0, 490.5]
i = bisect_left(f, c)
if i > 5: i = 5
print(h[i] if abs(c-f[i]) < abs(c-f[i+1]) else h[i+1])