import sys
input = sys.stdin.readline
from math import gcd

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

def f(x,y):
    if gcd(x,y)!=1:
        return 0
    else:
        return x*y-x-y+1


if N==2:
    ANS=f(A[0],A[1])
    print(ANS)
    print(1,2)
elif N==3:
    X=f(f(A[0],A[1]),A[2])
    Y=f(f(A[0],A[2]),A[1])
    Z=f(f(A[1],A[2]),A[0])

    MIN=min(X,Y,Z)

    print(MIN)
    if MIN==X:
        print(1,2)
        print(1,2)
    elif MIN==Y:
        print(1,3)
        print(1,2)
    else:
        print(2,3)
        print(1,2)
else:
    print(0)
    O=[]
    E=[]

    for i in range(N):
        if A[i]%2==1:
            O.append(i)
        else:
            E.append(i)

    if len(E)>=2:
        print(E[0]+1,E[1]+1)
        for i in range(N-1,1,-1):
            print(1,i)
    elif len(O)>=4:
        print(O[-1]+1,O[-2]+1)
        print(O[-3]+1,O[-4]+1)
        for i in range(N-2,1,-1):
            print(1,i)
    else:
        print(O[-1]+1,O[-2]+1)
        A.pop(O[-1])
        A.pop(O[-2])

        for i in range(len(A)):
            if A[i]%2==0:
                print(i+1,N-1)
                break

        for i in range(N-2,1,-1):
            print(1,i)