toI(s=readline()) = parse(Int,s)
toVI(s=readline()) = map(toI,eachsplit(s))
rep(f,n) = [f() for _ in 1:n]
@enum YN Yes=1 No=0

function (@main)(ARGS)
    n,m = toVI()
    s = toVI()
    t = toVI()
    solve(n,m,s,t) |> println
end

function solve(n,m,s,t)
    sort!(s)
    ok = 0; ng = m+1
    mx = 0
    while ng-ok > 1
        x = (ok+ng)÷2
        u = t[1:x] |> sort!
        mx = 0
        for si in s
            if si ≥ get(u,1,1<<30)
                mx = max(mx,si-popfirst!(u))
            end
        end
        if isempty(u)
            ok = x
        else
            ng = x
        end
    end
    return mx
end