n=int(input())
X=2*10**5
f=[]
for i in range(2,X):
  if n%i==0:
    while n%i==0:
      n//=i
      if len(f)>0 and f[-1]==2 and i==2:
        f.pop()
        f+=[4]
      else:
        f+=[i]
if n>1:
  f+=[n]
if len(f)+sum(f)>X:
  print(-1)
  exit()
print(len(f)+sum(f))
for i in range(len(f)-1):
  print(i+1,i+1+1)
c=len(f)
for i in range(len(f)):
  for j in range(f[i]):
    print(i+1,c+j+1)
  c+=f[i]
print(*(["b"]*len(f)+["g"]*sum(f)))