import math

n = int(input())
A = list(map(int,input().split()))

if 1 in A:
    assert False
    print(1)
    f = A.index(1) + 1

    s = 2 if f == 1 else 1

    print(f,s)
    for i in range(n-2):
        print(n-1-i,1)

    exit()

if 0 in A:
    assert False
    print(0)

    f = A.index(0) + 1

    s = 2 if f == 1 else 1

    print(f,s)
    for i in range(n-2):
        print(n-1-i,1)

    exit()


dic = {}
target = []
for i,a in enumerate(A,1):

    now = a
    for j in range(2,int(a**0.5)+1):
        if now%j:
            continue
        if j in dic:
            target = [i,dic[j]]
            break

        while now % j == 0:
            now //= j
        dic[j] = i
        
    if now == 1:
        continue
    j = now
    if j in dic:
        target = [i,dic[j]]
        break
    
    dic[j] = i


if target:
    print(0)
    assert target[0] != target[1]

    print(*target)
    for i in range(n-2):
        print(1,n-1-i)

    exit()

even = []
odd = []
for i,a in enumerate(A,1):
    if a%2:
        odd.append(i)
    else:
        even.append(i)


def get(A):

    ans = (A[0]-1) * (A[1]-1)


    for i in range(2,n):
        if math.gcd(ans,A[i]) != 1:
            return 0
        ans = (ans-1)*(A[i]-1)

    return ans
if (n == 3 and even == []) or n == 2:
    print(get(A))
    for i in range(n-1):
        print(1,2)

    exit()


print(0)

assert len(even) < 2
if even:

    f = odd.pop()
    s = odd.pop()

    print(f,s)
    
    x = even[0]
    m = 0
    if x > f:
        m += 1
    if x > s:
        m += 1
    x -= m

    print(x,n-1)
    for i in range(n-3):
        print(1,n-2-i)

else:
    print(1,2)
    print(1,2)
    print(n-2,n-3)
    for i in range(n-4):
        print(1,n-3-i)