h=list(int(i) for i in input().split())
s=['a','b','c']

for i in range(len(h),2,-1):
    for j in range(1,i):
        if h[j-1]>h[j]:
            h[j-1],h[j]=h[j],h[j-1]
            s[j-1],s[j]=s[j],s[j-1]

for i in s:
    print(i)