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()
    a = toVI()
    res = solve(n,m,a)
    println(length(res))
    for (s,l) in res
        println(s," ",l)
    end
end

function solve(n,m,a)
    res = Tuple{Int,Int}[]
    now = -1
    for x in a
        if now+1 == x
            s,l = res[end]
            res[end] = (s,l+1)
        else
            push!(res,(x,1))
        end
        now = x
    end
    res
end