When a piece of paper is folded in half, its thickness doubles. You have a piece of paper with a thickness of $1 \text{ cm}$. You want the paper to have a thickness of at least $n \text{ cm}$. How many times you need to fold the paper at least to achieve this?
### Input
- A line containing an integer $n$.
### Output
- Print an integer which is the minimum number of folds.
### Constraints
- $1 \le n \le 10^{18}$.
### Sample test
```
7
```
Output:
```
3
```
