#include <bits/stdc++.h>
using namespace std;
template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl
using ll = long long;
const int maxn = 1e6 + 5;
int n;
int dp[maxn][5];
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin>>n;
string a, b;
cin>>a;
cin>>b;
for (int i=0; i<=n; i++) {
for (int j=0; j<3; j++) {
dp[i][j] = n+10;
}
}
//0: off
//1: on
//2: do nothing
auto go = [&](int op, char c) {
if (op==0) return '0';
if (op==1) return '1';
return c;
};
dp[0][2] = 0;
for (int i=0; i<n; i++) {
for (int p=0; p<3; p++) {
for (int j=0; j<3; j++) {
int cur = dp[i][p];
//new operation
if (j!=p && j!=2) {
cur++;
}
//initiate flip
if ((i==0 || go(p,a[i-1])==b[i-1]) && go(j,a[i])!=b[i]) {
cur++;
}
dp[i+1][j] = min(dp[i+1][j], cur);
}
}
}
int res = n+10;
for (int x=0; x<3; x++) {
res = min(res, dp[n][x]);
}
cout<<res<<endl;
return 0;
}
