#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int n,ans=0x3f3f3f3f;
char s[5050],t[5050];
void work(int x)
{
	int res=0;
	for(int i=1;i<x;++i)if(s[i]!=s[i+1])res+=i;
	int p=0;
	for(int i=x;i<=n;++i)
		if(s[i]!=s[i+1])
		{
			if(!p&&t[1]!=s[i+1])res+=i;
			else
			{
				while(t[p]==t[p+1])++p;
				res+=abs(i-p);
				if(p!=n)++p;
			}
		}
	for(int i=p;i<=n;++i)
		if(t[i]!=t[i+1])res+=n-i;
	ans=min(ans,res);
}
int main()
{
	scanf("%d %s %s",&n,s+1,t+1);
	s[0]=s[1]^1,s[n+1]=s[n]^1;
	t[0]=t[1]^1,t[n+1]=t[n]^1;
	for(int i=0;i<=n;++i)if(!i||(s[i-1]!='1'&&s[i]=='1'))work(i);
	swap(s,t);
	for(int i=0;i<=n;++i)if(!i||(s[i-1]!='1'&&s[i]=='1'))work(i);
	printf("%d",ans);
	return 0;
}
