#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define pb push_back
#define all(a) a.begin(), a.end()
// #define endl "\n"
void printVector(vector<int> a){
for (auto x: a) cout << x << " ";
cout << endl;
}
void solve(){
int n; cin >> n;
string a, b; cin >> a >> b;
vector<int> A(n+5), B(n+5);
FOR(i,1,n+1){
if (a[i-1] == '0') A[i] = 0;
else A[i] = 1;
if (b[i-1] == '0') B[i] = 0;
else B[i] = 1;
}
int prev1 = 0; int prev2 = 0;
int prev3 = 0;
vector<int> dp(n+5, 1e9);
dp[0] = 0;
FOR(i,1,n+1){
// if (i == 8) cout << prev1 << prev2 << endl;
dp[i] = min(dp[i], dp[prev1]+1);
if (A[i] == B[i]) prev1 = i;
if (A[i] != B[i]) prev3 = i;
int t = 0;
if (prev3 > prev2) t = 1;
dp[i] = min(dp[i], dp[prev2]+t);
if (B[i] != B[i+1]) prev2 = i;
}
// printVector(dp);
cout << dp[n] << endl;
}
int32_t main(){
ios::sync_with_stdio(false);cin.tie(nullptr);
int t = 1; // cin >> t;
while (t--) solve();
}
