#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
string x, y;
int dp[1001000][2];
int main(){
cin.tie(NULL);
ios_base::sync_with_stdio(false);
int n;
cin >> n >> x >> y;
int pt[2] = {-2, -2}, pt2=-2;
if (x[0]!=y[0]) dp[0][0]=1, pt2=0;
dp[0][1] = 1;
pt[y[0]-'0']=0;
for (int i=1;i<n;i++){
if (x[i]==y[i]) dp[i][0]=min(dp[i-1][0], dp[i-1][1]);
else{
if (x[i-1]!=y[i-1]) dp[i][0] = min(dp[i-1][0], dp[i-1][1]+1);
else if (pt2==-2) dp[i][0] = min(dp[i-1][0], dp[i-1][1])+1;
else dp[i][0] = min(min(dp[i-1][0], dp[i-1][1]), dp[pt2][0])+1;
pt2=i;
}
if (y[i-1]==y[i]) dp[i][1] = min(dp[i-1][1], dp[i-1][0]+1), pt[y[i]-'0']=i;
else{
if (pt[y[i]-'0']==-2) dp[i][1] = min(dp[i-1][0], dp[i-1][1])+1;
else dp[i][1] = min(min(dp[i-1][0], dp[i-1][1]), dp[pt[y[i]-'0']][1])+1;
pt[y[i]-'0']=i;
}
}
/*for (int i=0;i<n;i++) cout << dp[i][0] << ' ';
cout << '\n';
for (int i=0;i<n;i++) cout << dp[i][1] << ' ';
cout << '\n';*/
for (int i=1;i<n;i++){
assert(min(dp[i][0], dp[i][1])-min(dp[i-1][0], dp[i-1][1])<=1);
assert(dp[i][0]-dp[i-1][0]<=1);
assert(dp[i][1]-dp[i-1][1]<=1);
assert(min(dp[i][0], dp[i][1])-min(dp[i-1][0], dp[i-1][1])>=0);
//assert(dp[i][0]-dp[i-1][0]>=0);
assert(dp[i][1]-dp[i-1][1]>=0);
assert(dp[i][1]-dp[i][0]<=1);
}
cout << min(dp[n-1][0], dp[n-1][1]);
return 0;
}
