CF622A.Infinite Sequence

普及/提高-

通过率：0%

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题目描述

Consider the infinite sequence of integers: $1,1,2,1,2,3,1,2,3,4,1,2,3,4,5...$ . The sequence is built in the following way: at first the number $1$ is written out, then the numbers from $1$ to $2$ , then the numbers from $1$ to $3$ , then the numbers from $1$ to $4$ and so on. Note that the sequence contains numbers, not digits. For example number $10$ first appears in the sequence in position $55$ (the elements are numerated from one).

Find the number on the $n$ -th position of the sequence.

输入格式

The only line contains integer $n$ ( $1<=n<=10^{14}$ ) — the position of the number to find.

Note that the given number is too large, so you should use $64$ -bit integer type to store it. In C++ you can use the long long integer type and in Java you can use long integer type.

输出格式

Print the element in the $n$ -th position of the sequence (the elements are numerated from one).

输入输出样例

输入#1
```
3
```
输出#1
```
2
```
输入#2
```
5
```
输出#2
```
2
```
输入#3
```
10
```
输出#3
```
4
```
输入#4
```
55
```
输出#4
```
10
```
输入#5
```
56
```
输出#5
```
1
```

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