X=int(input())
g=[]
while X%4==0:
    g.append(4)
    X//=4
for i in range(2,200000):
    while X%i==0:
        g.append(i)
        X//=i
if X!=1:
    print(-1)
    exit()
if len(g)==0:
    g.append(1)
if sum(g)+len(g)>200000:
	print(-1)
	exit()
print(sum(g)+len(g))
c=["b"]*len(g)+["g"]*sum(g)
pos=len(g)+1
for i in range(len(g)):
    if i!=0:
        print(i,i+1)
    for j in range(g[i]):
        print(i+1,pos)
        pos+=1
print(*c)
print("余計な文字列")