def quotient_range(n):
  ret=[]
  i=1
  while i<=n:
    q=n//i
    j=n//q+1
    ret.append((i,j))
    i=j
  return ret

def floor_sum(n,m,a,b):
  ans=0
  while True:
    if a>=m:
      ans+=(n-1)*n*(a//m)//2
      a%=m
    if b>=m:
      ans+=n*(b//m)
      b%=m
    y_max=(a*n+b)//m
    x_max=(y_max*m-b)
    if y_max==0:
      return ans
    ans+=(n-(x_max+a-1)//a)*y_max
    n,m,a,b=y_max,a,m,(a-x_max%a)%a

def mertens_table(n):
  if n==0:
    return [[0],[0]]
  b=10**4
  small=[1]*(n//b+1)
  large=[1]*(b+1)
  small[0]=0
  large[0]=0
  
  prime=[1]*(n//b+1)
  for p in range(2,n//b+1):
    if not prime[p]:
      continue
    for j in range(p,n//b+1,p):
      if j>p:
        prime[j]=0
      if j%(p*p)==0:
        small[j]=0
      else:
        small[j]*=-1
  
  for i in range(1,n//b):
    small[i+1]+=small[i]
  
  for i in range(b,0,-1):
    l=2
    while l<=n//i:
      q=n//(i*l)
      r=n//(i*q)+1
      if i*l<=b:
        large[i]-=large[i*l]*(r-l)
      else:
        large[i]-=small[n//(i*l)]*(r-l)
      l=r
  return small,large

def range_g(L,R,P,Q):
  return floor_sum(R,Q,P,0)-floor_sum(L,Q,P,0)

def count(n,P,Q):
  res=0
  for L,R in QR:
    x=n//L
    if x<len(small):
      res+=small[x]*range_g(L,R,P,Q)
    else:
      res+=large[n//x]*range_g(L,R,P,Q)
  return res

for _ in range(1):
  n,k=map(int,input().split())
  small,large=mertens_table(n)
  QR=quotient_range(n)
  c=count(n,n*n-1,n*n)
  if k==c+1:
    print('1/1')
    continue
  if k<=c:
    rev=False
  elif k<=2*c+1:
    rev=True
    k=2*c+2-k
  else:
    print(-1)
    continue

  ng,ok=-1,n*n
  while ok-ng>1:
    mid=(ok+ng)>>1
    if count(n,mid,n*n)>=k:
      ok=mid
    else:
      ng=mid

  ng2,ok2=0,n*n
  while ok2-ng2>1:
    mid=(ok2+ng2)>>1
    cnt1=floor_sum(mid,n*n,ok-1,ok-1)
    cnt2=floor_sum(mid,n*n,ok,ok)
    if cnt1!=cnt2:
      ok2=mid
    else:
      ng2=mid
  
  den=ok2
  num=ok*den//(n*n)
  if rev:
    den,num=num,den
  print(str(num)+'/'+str(den))