#ifdef Home
#define _GLIBCXX_DEBUG
#endif // Home
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int inf = 1e9;
// first
// memory optimization
// second
// 0 - all 0,
// 1 - all 1
// 2 - no changes,
// thrid
// 0 not have xor
// 1 have xor
main() {
#ifdef Home
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif // Home
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, cr = 1, pr = 0;
string a, b;
cin >> n >> a >> b;
vector < vector < vector < int > > > dp(2, vector < vector < int > > (3, vector < int > (2, inf)));
dp[pr][2][0] = 0;
for(int i = 0; i < n; ++ i) {
dp[cr] = {{inf, inf}, {inf, inf}, {inf, inf}};
if(a[i] == b[i]) {
dp[cr][2][0] = min({dp[pr][2][0], dp[pr][2][1], dp[pr][1][0], dp[pr][1][1], dp[pr][0][0], dp[pr][0][1]});
} else {
dp[cr][2][1] = min({dp[pr][2][0] + 1, dp[pr][2][1], dp[pr][1][0] + 1, dp[pr][1][1], dp[pr][0][0] + 1, dp[pr][0][1]});
}
if(b[i] == '0') {
dp[cr][0][0] = min({dp[pr][0][0], dp[pr][2][0] + 1, dp[pr][2][1] + 1,
dp[pr][0][1], dp[pr][1][0] + 1, dp[pr][1][1] + 1});
dp[cr][1][1] = min({dp[pr][1][1], dp[pr][1][0] + 1, dp[pr][2][1] + 1,
dp[pr][0][1] + 1, dp[pr][2][0] + 2, dp[pr][0][0] + 2});
} else {
dp[cr][1][0] = min({dp[pr][1][0], dp[pr][2][0] + 1, dp[pr][2][1] + 1,
dp[pr][1][1], dp[pr][0][0] + 1, dp[pr][0][1] + 1});
dp[cr][0][1] = min({dp[pr][0][1], dp[pr][0][0] + 1, dp[pr][2][1] + 1,
dp[pr][1][1] + 1, dp[pr][2][0] + 2, dp[pr][1][0] + 2});
}
swap(cr, pr);
}
cout << min({dp[pr][0][0], dp[pr][0][1], dp[pr][1][0], dp[pr][1][1], dp[pr][2][0], dp[pr][2][1]});
}
