s=input()
a=[0]*26
for i in s:
    if "A"<=i<="Z":
        a[ord(i)-ord("A")]+=1
    elif "a"<=i<="z":
        n=ord(i)-ord("a")
        a[n]=a[n]+1
imax=a[0]
for i in range(1,26):
    if imax<a[i]:
        imax=a[i]
s1="";s2=""
for i in range(len(a)):
    if imax==a[i]:
        s1=s1+" "+chr(ord("A")+i)
    elif a[i]==0:
        s2=s2+" "+chr(ord("A")+i)
print(s1[1:])
print(imax)
print(s2[1:])