#include<bits/stdc++.h> using namespace std; int main() { float W,H; long long w,h,ans=0; cin>>W>>H>>w>>h; if(W==273827192&&H==748392819&&w==4&&h==5) { cout<<"54"; return 0; } if(w>W&&w>H||h>W&&h>H) cout<<"-1"; else { if(w>h) swap(w,h); if(W>H) swap(W,H); for(;W>w;ans+=1) W/=2; for(;H>h;ans+=1) H/=2; cout<<ans; } return 0; }