w=as.raw(46:126)
for(r in strsplit(readLines("stdin")," ")){m=sapply(r,function(l)w%in%charToRaw(l))
for(i in 1:4)m=m%*%t(m)
u=apply(!!m,2,function(x)rawToChar(w[x]))
u=u[u>""]
write(u[order(nchar(u))[c(1,length(u))]],1,2)}