#include <iostream>
#include <vector>
using namespace std;
using ll=long long;
bool can(ll K,ll H,ll N)
    {
    vector<ll> dp(H+1,0);
    for(int i=1;i<=K;i++)
        {
        for(int j=H;j>=1;j--)
            {
            dp[j]=dp[j]+dp[j-1]+1;
            }
        //dp[0]=i;
        if(dp[H]>=N)return true;
        }
    return false;
    }


int main()
{
    ll n,h;cin>>n>>h;
    ll low=1,high=n;
    ll ans=high;
    while(low<=high)
        {
        ll m=(low+high)/2;
        if(can(m,h,n))
            {
            ans=m;
            high=m-1;
            }
        else low=m+1;
        }
    cout<<ans;
    return 0;
}