from bisect import bisect_left
n = int(input())
a = list(map(int, input().split()))
l = sorted(a)[-500]
p = []
for i, v in enumerate(a):
    if v > l and (not p or p[-1] < i-50): p.append(i)
d = [p[i+1]-p[i] for i in range(len(p)-1)]
m = len(d)//3
c = n/(sum(sorted(d)[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])