Problem:
Score : 200 points

Problem Statement

There is a kangaroo at coordinate 0 on an infinite number line that runs from left to right, at time 0.
During the period between time i-1 and time i, the kangaroo can either stay at his position, or perform a jump of length exactly i to the left or to the right.
That is, if his coordinate at time i-1 is x, he can be at coordinate x-i, x or x+i at time i.
The kangaroo's nest is at coordinate X, and he wants to travel to coordinate X as fast as possible.
Find the earliest possible time to reach coordinate X.

Constraints

X is an integer.

1≤X≤10^9

Input

The input is given from Standard Input in the following format:

X

Output

Print the earliest possible time for the kangaroo to reach coordinate X.

Sample Input 1

6

Sample Output 1

3

The kangaroo can reach his nest at time 3 by jumping to the right three times, which is the earliest possible time.

Sample Input 2

2

Sample Output 2

2

He can reach his nest at time 2 by staying at his position during the first second, and jumping to the right at the next second.

Sample Input 3

11

Sample Output 3

5

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

/*----------------------------------------------------*
* लेखक --> अमित सिंह
* संस्थान --> राष्ट्रीय प्रौद्योगिकी संस्थान, कुरुक्षेत्र
*-----------------------------------------------------*/
   #include <bits/stdc++.h>
   using namespace std;
   #define ll long long
   #define w(t) int t; cin>>t; while(t--)
   #define fo(i,n) for(int i=0;i<n;i++)
   #define endl "\n" 
   #define MOD 1000000007
   void Tez(){
      ios::sync_with_stdio(0);
      cin.tie(0);
      cout.tie(0);
   }
   int main(){
      Tez();
      int x;
      cin>>x;
      ll t=0,c=0;
      while(true){
          if(c+t==x){
              break;
          }
          t++;
          if(c+t+t+1<=x){
              c+=t;
          }
      }
      cout<<t;
      return 0;
   }