import math
class Sieve_of_Eratosthenes:

    def __init__(self, n):
        self.n = n
        self.p_list=[]
        self.minp = [0] * (n + 1)

        for i in range(2, n + 1):
            if self.minp[i] == 0:
                self.p_list.append(i)
                self.minp[i] = i
                for j in range(i * i, n + 1, i):
                    if self.minp[j] == 0:
                        self.minp[j] = i

    def prime_factorization(self, n):
        factors = {}
        prev_p = -1

        while n > 1:
            p = self.minp[n]
            if p != prev_p:
                factors[p] = 1
                prev_p = p
            else:
                factors[p] += 1
            n //= p

        return factors

era=Sieve_of_Eratosthenes(2*10**5)

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

dics=[era.prime_factorization(A[i]) for i in range(N)]
#print(dics)

flag=[-1 for i in range(2*10**5)]
for i in range(N):
    for j in dics[i].keys():
        if flag[j]==-1:
            flag[j]=i
        else:
            print(0)
            print(flag[j]+1,i+1)
            for i in range(N-2):
                print(1,N-1-i)
            exit()

def f(x,y):
    if math.gcd(x,y)==1:
        return (x-1)*(y-1)
    return 0
      
if N==2:
    M=f(A[0],A[1])
    print(M)
    print(1,2)
    exit()
    
if N==3:
    ans1=(f(A[2],f(A[0],A[1])),(1,2),(1,2))
    ans2=(f(A[0],f(A[1],A[2])),(2,3),(1,2))
    ans3=(f(A[1],f(A[0],A[2])),(1,3),(1,2))

    ls=[ans1,ans2,ans3]
    ls.sort()
    print(ls[0][0])
    print(*ls[0][1])
    print(*ls[0][2])
    exit()
    
print(0)
print(1,2)
print(1,2)
print(N-3,N-2)
for i in range(N-3,1,-1):
    print(1,i)