#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

ULL n, h;

bool check(ULL t) {

    ULL res;

    if(t >= h) res = (+t)*t/ + t*(t-)/ - h*(h-)/;

    else res = (+t)*t/;

    if(res >= n) return true;

    else return false;

}

bool Check(ULL t) {

    ULL res;

    if(t >= h) res = (+t)*t - h*(h-)/;

    else res = (+t)*t/;

    if(res >= n) return true;

    else return false;

}

int main() {

    scanf("%llu%llu", &n, &h);

    ULL l = , r = 2e9, m = (l+r) >> ;

    while(l < r) {

        if(check(m)) r = m;

        else l = m+;

        m = (l+r) >> ;

    }

    ULL ans;

    if(m >= h) ans = *m - h;

    else ans = m;

    l = , r = 2e9, m = (l+r) >> ;

    while(l < r) {

        if(Check(m)) r = m;

        else l = m+;

        m = (l+r) >> ;

    }

    if(m >= h) ans = min(ans, *m - h + );

    else ans = min(ans, m);

    printf("%llu\n", ans);

    return ;

}