N,M,K = map(int,input().split())
T = list(map(int,input().split()))
if T.count(T[0]) == M:
    print(min(T[0],M))
    for i in range(min(T[0],M)):
        print(i+1,i+1)
else:
    D = {}
    for i in range(1,N+1):
        D[i] = []
    for i in range(M):
        D[T[i]].append(i+1)
    V = []
    for i in range(1,N+1):
        k = 0
        for j in range(i,N+1):
            eleje = 0
            while k < K and eleje < len(D[j]):
                k += 1
                V.append([D[j][eleje],i])
                eleje += 1
            D[j] = D[j][eleje:]
            if k == K:
                break
    print(len(V))
    for munka,nap in V:
        print(munka,nap)