#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;
string tmpx, tmpy;
cin >> n >> tmpx >> tmpy;
int idx1=0, idx2=n;
for (;idx1<n && tmpx[idx1]==tmpy[idx1];idx1++);
for (;idx2 && tmpx[idx2-1]==tmpy[idx2-1];idx2--);
for (int i=idx1;i<idx2;i++) x.push_back(tmpx[i]);
for (int i=idx1;i<idx2;i++) y.push_back(tmpy[i]);
n = idx2-idx1;
//cout << n << '\n' << x << '\n' << y << '\n';
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] = 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;
}
dp[i][1] = min(dp[i][1], dp[i][0]+1);
}
/*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';*/
if (n>=1) cout << min(dp[n-1][0], dp[n-1][1]);
else cout << 0;
return 0;
}
