题目：P11560

rt，测试点7,13,18,20,22,24WA

#include <bits/stdc++.h>
using namespace std;
unsigned long long a,b,ans;
int main()
{
    ios::sync_with_stdio(false);
    cout.tie(0);cin.tie(0);
    cin>>a>>b;
    if(b==a) { cout<<0; return 0; }
    if(b<a) { cout<<a-b; return 0; }
    unsigned long long i=a;
    for(;i<=b;i*=2) ans++;
    ans=min(i-b,b-i/2)+ans-1;
    cout<<ans;
    return 0;
}