PROGRAMMING:Binary to decimal

Now $$Keven $$has a binary number $$n $, but he wants to know the number represented in decimal system. Can you help him?
###Input format:
Give $$n $$in one line for binary numbers.
Input to ensure that the length of the binary number does not exceed $$20$$
###Output format:
Output the number of $$n $$in decimal on one line.
Make sure it doesn't exceed $1000000$$
###Input example:
Here is a set of inputs. For example:
```in
one thousand and ten
```
###Output example:
The corresponding output is given here. For example:
```out
ten
```







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