main=do
 s<-getLine
 t<-getLine
 let sl=length s
 let tl=length t
 let ok=[map(\c->if c=='?' then 'a' else c)$(take i s)++t++(drop(i+tl)s)|i<-[0..sl-tl],f$zip(take tl$drop i s)t]
 putStrLn$if null ok then"UNRESTORABLE"else minimum ok
f[]=True
f((a,b):s)=if a/='?'&&a/=b then False else f s