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    <th style="width:2em;">#</th>
    <th style="width:12em;">Author</th>
    <th style="width:2em;">Problem</th>
    <th style="width:2em;">Lang</th>
    <th style="width:8em;">Verdict</th>
    <th style="width:2em;">Time</th>
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    <td>25518521</td>
    <td>
            Contestant:<br/>
<a href="/profile/jvj_iit" title="Specialist jvj_iit" class="rated-user user-cyan">jvj_iit</a>    </td>
    <td>
        <a title="C - Anton and Fairy Tale" href="/contest/785/problem/C">785C</a>
         - <span title="problem revision">127</span>
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    <td>
    Python 2
    </td>
    <td>
    <span class='verdict-accepted'>Accepted</span>
    </td>
    <td>
        62 ms
    </td>
    <td>
        4556 KB
    </td>
    <td>2017-03-15 19:13:29</td>
    <td>2017-03-15 20:46:25</td>
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                                    .removeClass("top").removeClass("bottom")
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                                    .removeClass("dark");
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                                $(this).find("tr:last td").addClass("bottom");
                                $(this).find("tr:odd td").addClass("dark");
                                $(this).find("tr td:first-child, tr th:first-child").addClass("left");
                                $(this).find("tr td:last-child, tr th:last-child").addClass("right");
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    <div class="roundbox " style="margin-top:2em;font-size:1.1rem;">
            <div class="roundbox-lt">&nbsp;</div>
            <div class="roundbox-rt">&nbsp;</div>
        <div class="caption titled">&rarr; Source
            <div class="top-links">
            </div>
        </div>
    <pre class="prettyprint lang-py program-source" style="padding: 0.5em;">n=0
m=0

def ByDay(day) :
	if day <= m :
		return n-day
	return n - m + m*(day-m) - day*(day+1)/2 + m*(m+1)/2

def binary() :
	first = 1
	last = 1000000000000000000

	while first + 1 < last :
		mid = (first+last)/2

		if ByDay(mid) <= 0 :
			last = mid
		else :
			first = mid
	if ByDay(first) <= 0 :
		return first
	else :
		return last					

n,m = map(int,raw_input().strip().split())


print binary()	
