#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace __gnu_pbds;
using namespace std;
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int g(int x, int k) {
if(k==0) return 0;
if(k==1) return 1;
if(k==2) return 1;
if(k==3) return 0;
if(k==4) return x^1;
return x;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n;
cin >> n;
int inf = 1e7;
vector<vector<int>> dp(n+1, vector<int>(6, inf));
string x, y;
cin >> x >> y;
vector<int> a(n+1), b(n+1);
for(int i=0; i<n; ++i) {
if(x[i]=='0') a[i+1] = 0;
else a[i+1] = 1;
if(y[i]=='0') b[i+1] = 0;
else b[i+1] = 1;
}
vector<vector<pair<int, int>>> ways = {
{{5,1}, {2,0}},
{{5,1}, {3,0}},
{{0,1}, {4,1}},
{{1,1}, {4,1}},
{{5,1}, {2,0}, {3,0}},
{{0,0}, {1,0}, {2,0}, {3,0}, {4,0}, {5,0}}
};
for(int i=0; i<=5; ++i) ways[i].push_back({i,0});
dp[0][5] = 0;
for(int i=1; i<=n; ++i) {
for(int k=0; k<=5; ++k) {
if(g(a[i],k) != b[i]) continue;
for(auto[l, cost] : ways[k]) {
dp[i][k] = min(dp[i][k], dp[i-1][l] + cost);
}
}
}
auto get_ans = [&](int i) {
int ans = inf;
for(int k=0; k<=5; ++k) ans = min(ans, dp[i][k]);
return ans;
};
cout << get_ans(n) << "\n";
return 0;
}
