f=tcrossprod
for(l in strsplit(readLines("stdin")," ")){g=apply(f(f(f(sapply(lapply(l,charToRaw),"%in%",x=r<-as.raw(46:127))))),1,function(x)rawToChar(r[x>0]))
g=g[g>""]
write(g[order(nchar(g))[c(1,length(g))]],1,2)}
Note that non-ascii characters in the above source code will be escaped (such as \x9f).