#include "bits/stdc++.h"
using namespace std;
string s, t;
int n;
const int inf = 1e9;
int mem[2][3][1000010];
int dp(int cur, int xr, int col) {
if(cur == n) return 0;
int &ans = mem[xr][col][cur];
if(ans != -1) return ans;
ans = inf;
for(int i = 0; i < 2; i++) {
for(int j = 0; j < 3; j++) {
int cost = 0;
if(xr != i && i > 0) ++cost;
if(col != j && j > 0) ++cost;
int c = (j > 0) ? (j - 1) : (t[cur] - '0');
c ^= i;
if(c == (s[cur] - '0')) {
ans = min(ans, dp(cur + 1, i, j) + cost);
}
}
}
return ans;
}
int main(int argc, char const *argv[])
{
memset(mem, -1, sizeof mem);
cin >> n >> t >> s;
cout << dp(0, 0, 0) << endl;
return 0;
}
