from bisect import bisect_left
n = int(input())
a = list(map(int, input().split()))
c = 0
for i in range(1, n-1):
    if a[i-1] <= a[i] >= a[i+1]: c += 1
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(v-f[i]) < abs(v-f[i+1]) else h[i+1])