from math import gcd
n = int(input())
a = list(map(int,input().split()))
def f(x,y): return 0 if gcd(x,y)>1 else (x-1)*(y-1)
if n==2: print(f(a[0],a[1])); print(1,2)
elif n==3:
    p,q,r = f(f(a[0],a[1]),a[2]),f(f(a[1],a[2]),a[0]),f(f(a[2],a[0]),a[1])
    if q>=p<=r: print(p); print(1,2); print(1,2)
    elif q<=r: print(q); print(2.3); print(1,2)
    else: print(r); print(3,1); print(1,2)
else:
    print(0); print(1,2); print(1,2)
    for i in range(n-2,1,-1): print(1,i)