#include<bits/stdc++.h>
using namespace std;
const int N = 1e6 + 1;
const int inf = 1e9 + 7;
int f[N][3][2];
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n; cin >> n;
string a; cin >> a;
string b; cin >> b;
for(int i = 0 ; i < 3 ; ++i)
for(int j = 0 ; j < 2 ; ++j) if (i || j)
f[0][i][j] = inf;
for(int i = 1 ; i <= n ; ++i) {
int x = a[i - 1] - '0';
int y = b[i - 1] - '0';
for(int j = 0 ; j < 3 ; ++j)
for(int k = 0 ; k < 2 ; ++k) {
int &F = f[i][j][k];
F = inf;
if (j == 0 && k != (x ^ y))
continue;
if (j == 1 && k != y) continue;
if (j == 2 && k == y) continue;
for(int t = 0 ; t < 3 ; ++t) {
F = min(F,f[i - 1][t][0] + (t != j && j > 0) + k);
F = min(F,f[i - 1][t][1] + (t != j && j > 0));
}
}
}
int ans = inf;
for(int i = 0 ; i < 3 ; ++i)
for(int j = 0 ; j < 2 ; ++j)
ans = min(ans,f[n][i][j]);
cout << ans << endl;
}
/*
13
1010010010100
0000111001011
*/
