local S_dash=io.read()
local S_dash_copy=S_dash
local T=io.read()

for i=#S_dash-#T+1,1,-1 do
    local subS=S_dash:sub(i,#T+i-1)
    local flag=true
    for j=1,#T do
        if subS:sub(j,j)~="?" and subS:sub(j,j)~=T:sub(j,j) then
            flag=false
        end
    end
    if flag and subS:gsub("?","")~="" then
        S_dash=S_dash:sub(1,i-1)..T..S_dash:sub(#T+i)
        break
    end
end
if S_dash==S_dash_copy then
    print("UNRESTORABLE")
else
    S=S_dash:gsub("?","a")
    print(S)
end