#include<bits/stdc++.h>
using namespace std;
int main()
{
long long int x,sum(0);
cin>>x;
for(long long int i=1; i<=1000000000; ++i)
{
sum+=i;
if(sum>=x)
{
cout<<i;
break;
}
}
}
### Prompt

Create a solution in cpp for the following problem:

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.

Examples

Input

6


Output

3


Input

2


Output

2


Input

11


Output

5

### Response

```cpp
#include<bits/stdc++.h>
using namespace std;
int main()
{
long long int x,sum(0);
cin>>x;
for(long long int i=1; i<=1000000000; ++i)
{
sum+=i;
if(sum>=x)
{
cout<<i;
break;
}
}
}
```