#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#define endl "\n"
typedef long long ll;
template<class T, class T2> inline ostream &operator <<(ostream &out, const pair<T, T2> &x) { out << x.first << " " << x.second; return out;}
template<class T, class T2> inline istream &operator >>(istream &in, pair<T, T2> &x) { in >> x.first >> x.second; return in;}
template<class T, class T2> inline bool chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline bool chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const ll mod = 1e9 + 7;
#define out(x) "{" << (#x) << ": " << x << "} "
const int MAX_N = 1e5 + 10;
ll dp[MAX_N][3][2];
string a, b;
int n;
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n >> a >> b;
a = "x" + a;
b = "x" + b;
for(int i = 0; i < MAX_N; i ++) {
for(int j = 0; j < 3; j ++) {
for(int k = 0; k < 2; k ++) {
dp[i][j][k] = mod;
}
}
}
dp[0][2][0] = 0;
for(int i = 1; i <= n; i ++) {
for(int j = 0; j < 2; j ++) {
for(int k = 0; k < 2; k ++) {
int curr = j;
if(k) {curr = (1 - curr);}
if(curr != b[i] - '0') {continue;}
for(int prevj = 0; prevj < 3; prevj ++) {
for(int prevk = 0; prevk < 2; prevk ++) {
int cost;
if(prevj != j) {
cost = 1;
} else {
cost = 0;
}
if(k == 1 && prevk != k) {
cost ++;
}
chkmin(dp[i][j][k], dp[i - 1][prevj][prevk] + cost);
}
}
}
}
if(a[i] == b[i]) {
for(int j = 0; j < 3; j ++) {
for(int k = 0; k < 2; k ++) {
chkmin(dp[i][2][0], dp[i - 1][j][k]);
}
}
} else {
for(int j = 0; j < 3; j ++) {
for(int k = 0; k < 2; k ++) {
chkmin(dp[i][2][1], dp[i - 1][j][k] + (1 - k));
}
}
}
}
ll ret = mod;
for(int i = 0; i < 3; i ++) {
for(int j = 0; j < 2; j ++) {
chkmin(ret, dp[n][i][j]);
}
}
cout << ret << endl;
return 0;
}
