S=io.read()
T=io.read()
print(S,T)
local s=#S
local t=#T
local res=false
local q=0
local news
local ans
while s>0 do
    if string.sub(S,s,s)=="?" or string.sub(S,s,s)==string.sub(T,t,t) then
        t=t-1
        if t==0 then
            q=s
            res=true
            news=string.sub(S,1,q-1)..T..string.sub(S,q+#T,#S)
            ans=string.gsub(news,"?","a")
            print(ans)
        end
        if string.sub(S,s-1,s-1)~="?" and string.sub(S,s-1,s-1)~=string.sub(T,t,t) then
            t=#T
        end
    end
    s=s-1
    if res==true then
        break
    end
end
if res==false then
    print("UNRESTORABLE")
end