N=int(input())
A=list(map(int,input().split()))
Y=[4360,4905,2616,2943,3270,3488,3924]
X=[round(N*100/Y[i]) for i in range(7)]
B=[]
for i in range(N):
  for j in range(10):
    B.append(A[i])
ANS=[0]*7
for i in range(N*10):
  for j in range(7):
    if B[i]==B[(i+X[j])%(N*10)]:
      ANS[j]+=1
print(chr(ord('A')+ANS.index(max(ANS)))+'4')