// https://oj.uz/submission/1054187
#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 1e6 + 6;
int n;
string a, b;
int f[maxn][3][2];
void solve() {
cin >> n >> a >> b;
a = ' ' + a;
b = ' ' + b;
memset(f, 0x3f, sizeof(f));
f[0][0][0] = 0;
for (int i = 1; i <= n; ++i) {
for (int j = 0; j < 3; ++j) {
for (int k = 0; k < 2; ++k) {
int cur = a[i] - '0';
if (j == 1) cur = 0;
if (j == 2) cur = 1;
cur ^= k;
for (int pj = 0; pj < 3; ++pj) {
for (int pk = 0; pk < 2; ++pk) {
if (cur == b[i] - '0') {
int cost = f[i - 1][pj][pk];
cost += (pj != j and j > 0);
cost += (k and !pk);
f[i][j][k] = min(f[i][j][k], cost);
}
}
}
}
}
}
int res = 1e9;
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 2; ++j) {
res = min(res, f[n][i][j]);
}
}
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
