#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e6+6;
int dp[MAXN][4][4];
/*
* 0 - nothing
* 1 - flip
* 2 - 0
* 3 - 1
*/
int a[MAXN],b[MAXN];
int main()
{
int n;
cin>>n;
for(int i=1;i<=n;i++)
{
char c;
cin>>c;
a[i]=c-'0';
}
for(int i=1;i<=n;i++)
{
char c;
cin>>c;
b[i]=c-'0';
}
for(int i=0;i<MAXN;i++)
{
for(int i1=0;i1<4;i1++)
for(int i2=0;i2<4;i2++)
{
dp[i][i1][i2]=MAXN+1;
}
}
dp[0][0][0]=0;
for(int i=1;i<=n;i++)
{
for(int i1=0;i1<4;i1++)
for(int i2=0;i2<4;i2++)
{
if(i1==0&&i2!=0)continue;
int a1=a[i];
if(i1==1)a1=1-a1;
if(i1==2)a1=0;
if(i1==3)a1=1;
if(i2==1)a1=1-a1;
if(i2==2)a1=0;
if(i2==3)a1=1;
if(a1!=b[i])continue;
dp[i][i1][i2]=min(dp[i][i1][i2],dp[i-1][i1][i2]);
for(int j=0;j<4;j++)dp[i][i1][i2]=min(dp[i][i1][i2],dp[i-1][i1][j]+(i2>0));
for(int j=0;j<4;j++)dp[i][i1][i2]=min(dp[i][i1][i2],dp[i-1][j][i1]+(i2>0));
for(int j=0;j<4;j++)dp[i][i1][i2]=min(dp[i][i1][i2],dp[i-1][i2][j]+(i1>0));
for(int j=0;j<4;j++)dp[i][i1][i2]=min(dp[i][i1][i2],dp[i-1][j][i2]+(i1>0));
for(int j1=0;j1<4;j1++)for(int j2=0;j2<4;j2++)dp[i][i1][i2]=min(dp[i][i1][i2],dp[i-1][j1][j2]+(i1>0)+(i2>0));
}
/*cout<<i<<":\n";
for(int i1=0;i1<2;i1++)
for(int i2=0;i2<2;i2++)
for(int i3=0;i3<2;i3++)
{
cout<<i1<<" "<<i2<<" "<<i3<<" "<<dp[i][i1][i2][i3]<<endl;
}*/
}
int ans=MAXN;
for(int i1=0;i1<4;i1++)
for(int i2=0;i2<4;i2++)
{
ans=min(ans,dp[n][i1][i2]);
}
cout<<ans<<endl;
return 0;
}
