#include<bits/stdc++.h>
using namespace std;
#define int int64_t
#define pb push_back
#define pii pair<int, int>
#define st first
#define nd second
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
int dp[1000009][8];
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
for(int i=0;i<=n;i++) {
for(int j=0;j<8;j++) {
dp[i][j] = 1e9;
}
}
dp[0][0] = 0;
string A, B;
cin >> A >> B;
for(int i=1;i<=n;i++) {
for(int j=0;j<8;j++) {
for(int k=0;k<8;k++) {
bool a = k&1;
bool b = k&2;
bool c = k&4;
if(a&&b) continue;
int New = A[i-1]-'0';
if(c) New = 1-New;
if(a) New = 1;
if(b) New = 0;
if(New!=B[i-1]-'0') continue;
bool ap = a&(!(j&1));
bool bp = b&(!(j&2));
bool cp = c&(!(j&4));
dp[i][k] = min(dp[i][k], dp[i-1][j]+ap+bp+cp);
}
}
}
int ans = 1e9;
for(int i=0;i<8;i++)
ans = min(ans, dp[n][i]);
cout << ans << "\n";
}
