var
  i,n,m,j,k,d,f,k2,k1,p : longint;
  a,b,c : array [1..100] of longint;
begin
  readln(n);
  readln(m);
  j:=1;
  i:=2;
    repeat
      if n mod i = 0 then
        begin
          a[j]:=i;
          n:=n div i;
          i:=2;
          k1:=k1+1;
          j:=j+1;
        end
      else
        i:=i+1;
    until n=1;
    i:=2;
    j:=1;
    repeat
      if m mod i = 0 then
        begin
          b[j]:=i;
          m:=m div i;
          i:=2;
          k2:=k2+1;
          j:=j+1;
        end
      else
        i:=i+1;
    until m=1;
    p:=1;
    for j:=1 to k1+k2 do
      if (a[j]<>b[j])then
        begin
          k:=k+1;
          c[p]:=b[j];
          p:=p+1;
          c[p]:=a[j];
          p:=p+1;
        end;
  for p:=1 to k do
  if (c[p]>3) then
  k:=11111111;
  if k=11111111 then
    writeln('-1')
  else
    writeln(k);
end.