PROGRAMMING:Step jumping
In recent years, step jumping has become more and more popular. Many college students practice step jumping every day. Some can jump up to two levels at a time, and some can jump up to three levels
Xiao Liu is the champion of our school's step jumping. He can see n steps at a time, but he doesn't want to finish it all at once. He wants to know how many ways he can finish n steps at most
###Input format:
Enter a positive integer n (n > 0, N in integer range)
###Output format:
Output the number of schemes corresponding to N steps. As the answer may be very large, please take the modulus for 1e9 + 7
###Input example:
Here is a set of inputs. For example:
```in
three
```
###Output example:
The corresponding output is given here. For example:
```out
four
```
answer：If there is no answer, please comment
Xiao Liu is the champion of our school's step jumping. He can see n steps at a time, but he doesn't want to finish it all at once. He wants to know how many ways he can finish n steps at most
###Input format:
Enter a positive integer n (n > 0, N in integer range)
###Output format:
Output the number of schemes corresponding to N steps. As the answer may be very large, please take the modulus for 1e9 + 7
###Input example:
Here is a set of inputs. For example:
```in
three
```
###Output example:
The corresponding output is given here. For example:
```out
four
```
answer：If there is no answer, please comment
