Farmer John ordered N of his cows (1 & le; N & le; 1000), each of which has one of two breeds Holsteins or Guernseys. He fixed this order as a string of N characters, each of which is either H or G respectively. Unfortunately, when the cows arrived at the farm and he lined them up again, they formed a different line from the original.
Let's call these two strings A and B, where A is the original string he wanted to see, B is the string that came out when the cows arrived. FD asked Cousin Ben for help.
After several months of work, Ben has created an amazing MCBF-3000 machine that can take any substring and change all Gs to Hs and all Hs to Gs. A. Help FD.
Input
The first line contains N, and the next two lines contain strings A and B. Each of the strings consists only of characters H and G.
Imprint
Print the minimum number of times the MCBF-3000 machine is used to transform string B into string A.
Examples
| # |
Input |
Output |
| 1 |
7
GHHHGHH
HHGGGHH
|
2 |