#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6 + 10;
int dp[maxn][65];
int mab(int fi, int se){
return fi + se * 4;
}
int transform(int x, int query){
if (query == 0)
return x;
else if (query == 1)
return 0;
else if (query == 2)
return 1;
else
return 1 ^ x;
}
int transfer(int q, int fi, int se){
q = transform(q, fi);
q = transform(q, se);
return q;
}
bool C(int x){
return x > 0;
}
int lcs[5][5];
int pd[257];
int cost(int fi, int se, int Fi, int Se){
if (pd[fi + 4 * se + 16 * Fi + 64 * Se] != -1)
return pd[fi + 4 * se + 16 * Fi + 64 * Se];
vector<int> a = {fi, se};
vector<int> b = {Fi, Se};
int cnt = C(Fi) + C(Se);
for (int i = 1; i <= 2; i++){
for (int j = 1; j <= 2; j++){
lcs[i][j] = max(lcs[i - 1][j], lcs[i][j - 1]);
if (a[i - 1] == 0 or b[i - 1] == 0)
continue;
lcs[i][j] = max(lcs[i][j], (lcs[i - 1][j - 1] + 1) * (a[i - 1] == b[j - 1]));
}
}
return pd[fi + 4 * se + 16 * Fi + 64 * Se] = cnt - lcs[2][2];
}
vector<int> go[2][2];
vector<pair<int,int> > vec[65];
int main(){
ios_base::sync_with_stdio(false);
memset(pd, -1, sizeof pd);
int n;
string s, t;
cin >> n >> s >> t;
memset(dp, 63, sizeof dp);
dp[0][0] = 0;
int answer = n;
for (int i = 0; i <= 3; i++){
for (int j = 0; j <= 3; j++){
int nex = transfer(0, i, j);
go[0][nex].push_back(mab(i, j));
nex = transfer(1, i, j);
go[1][nex].push_back(mab(i, j));
}
}
for (int i = 0; i <= 3; i++)
for (int j = 0; j <= 3; j++)
for (int x = 0; x <= 3; x++)
for (int y = 0; y <= 3; y++)
vec[mab(i, j)].push_back({mab(x, y), cost(x, y, i, j)});
for (int i = 1; i <= n; i++){
int me = (int)(s[i - 1] - '0');
int nex = (int)(t[i - 1] - '0');
for (auto it : go[me][nex])
for (auto to : vec[it])
dp[i][it] = min(dp[i][it], dp[i - 1][to.first] + to.second);
}
for (int i = 0; i < 65; i++)
answer = min(answer, dp[n][i]);
cout << answer << endl;
}
