#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
Int solve2(Int h, Int w){
  w=abs(w);
  Int ans=0;
  if(h>=w){
    ans+=(h-(w-1));
    h=w-1;
  }

  for(Int i=1;i<=h;i<<=1){
    Int j=min((i<<1)-1,h);
    Int len=j-i+1;
    ans+=len*(w/i);
    Int res=w%i;
    ans+=res;
  }
  return ans;
}

Int solve3(Int h,Int w){
  if(w>=1e7) return 0;

  auto start=clock();
  Int num=0;
  vector<Int> cnt(w+1,0);
  cnt[0]=h;
  while(1){
    if((double)(clock()-start)/CLOCKS_PER_SEC>=1.0) break;
    if(cnt[w]==h){
      return num;
    }
    for(Int i=0;i<w;i++){
      if(cnt[i]==0) continue;
      Int j=i+cnt[i];
      chmin(j,w);
      cnt[i]--;
      cnt[j]++;
      break;
    }
    num++;
  }

  return -1;
}

signed main(){
  Int h,w;
  cin>>h>>w;
  cout<<solve3(h,w)<<endl;
  return 0;
}