import math

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


def f(A,inds):
    ans = [[inds[-1],inds[-2]]]
    
    a1,a2 = A[-1],A[-2]
    num = 10**18
    if math.gcd(a1,a2) != 1:
        num = 0
    else:
        num = (a1-1)*(a2-1)

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

if n >= 4:
    print(0)
    for i in range(n-1):
        print(1,2)

else:

    inds = [i+1 for i in range(n)]

    res = 10**18
    ans = []
    for i in range(n):
        num,ans2 = f(A,inds)
        if num < res:
            res = num
            ans = ans2
        
        inds = inds[1:] + [inds[0]]
        A = A[1:] + [A[0]]
    
    print(res)
    for a in ans:
        print(*a)