N=int(input())
A=list(map(int, input().split()))

freq={'C4':261.6,
      'D4':294.3,
      'E4':327.0,
      'F4':348.8,
      'G4':392.4,
      'A4':436.0,
      'B4':490.5}

min_diff = 10000000000
for k,v in freq.items():
  n = int(44100/v)
  #print(k,v)
  #print(n)
  diff = sum([abs(A[i]-A[i+n]) for i in range(n)])/n
  #print(diff)
  if diff < min_diff:
    min_diff = diff
    ans = k
print(ans)