def g(u):import re;q=''.join([i for i in u.lower()if i in list(map(chr,range(97,123)))+list("'- ")]).split();Q=q.count;D=list(map(Q,set(q)));return['',max(q,key=Q)][1in map(D.count,D)] print(g(input()))
"That's... that's... that is just terrible!" he said.