#include<bits/stdc++.h>
#define ll long long
#define F first
#define S second
#define pb push_back
using namespace std;
const ll maxn = 1e5 + 7;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ll n = 0;
  cin >> n;
  ll c = 1;
  while ((c * (c + 1) / 2) < n)
    ++c;
  cout << c;
}

#include <bits/stdc++.h>
using namespace std;

typedef long long int ll;
#define All(a) (a).begin(),(a).end()
#define INF 2e18
#define MOD 1000000007

// ビットをずらすときは1LLを使え
// 有効桁のある小数を書く時はfixed + setorecisionを使え

int main(){
	ll n,ans;
  string s;
  cin >> s;
  cout << s[1] <<s[2]<<s[0]<< endl;
  
  
	/*for(ll i=0;i<n;i++){
		cin >> ;
	}*/


	//cout << ans << endl;
	return 0;
}
