Target = 5 * (10 ** 99)
Answer = []

def GetNearest(N, A):
    minx = 10 ** 100
    minid = -1
    for i in range(1, N):
        avg = (A[0] + A[i]) // 2
        if minx > abs(Target - avg):
            minx = abs(Target - avg)
            minid = i
    return minid

# Step 1. 入力
N = int(input())
A = [ 0 ] * N
for i in range(N):
    A[i] = int(input())

# Step 2. 一番近いやつと組む
idx1 = GetNearest(N, A)
avg1 = (A[0] + A[idx1]) // 2
A[0]    = avg1
A[idx1] = avg1
Answer.append([0, idx1])
next_tgt = 10 ** 100 - avg1

# Step 3. 貪欲法
while len(Answer) < 99:
    mincost = 10 ** 100
    minop = [-1, -1]
    for i in range(1, N):
        for j in range(i+1, N):
            avg = (A[i] + A[j]) // 2
            if mincost > abs(avg - next_tgt) and A[i] != A[j]:
                mincost = abs(avg - next_tgt)
                minop = [i, j]
    if minop == [-1, -1]:
        break
    avg2 = (A[minop[0]] + A[minop[1]]) // 2
    A[minop[0]] = avg2
    A[minop[1]] = avg2
    Answer.append(minop)

# Step 4. 一番近いやつと組む
idx3 = GetNearest(N, A)
avg3 = (A[0] + A[idx3]) // 2
A[0]    = avg3
A[idx3] = avg3
Answer.append([0, idx3])

# Step 5. 答えを出力
print(len(Answer))
for i in Answer:
    print(str(i[0] + 1) + " " + str(i[1] + 1))