include <bits/stdc++.h>

using namespace std;

int main() {

int n = 0, m, s = 0;
cin >> m;

while (s <= m) {
	n++;
	s = s + n;
}

cout << n;
return 0;
s//列数
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cout<<s
if(s>555555</s>){
cout<<56
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}
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} 哈哈 假的