#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n, dp[1001001][2][3];
string A, B;
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> A >> B;
for(int i=0;i<=n;i++) for(int j=0;j<=2;j++) fill(dp[i][j], dp[i][j]+3, n);
dp[0][0][2] = 0;
for(int i=1;i<=n;i++) {
int u = B[i-1]-'0';
for(int j=0;j<2;j++) dp[i][j][u] = min(dp[i-1][j][2]+1, dp[i-1][j][u]);
dp[i][1][u] = min(dp[i][1][u], dp[i-1][0][2]+2);
if(A[i-1] == B[i-1]) {
dp[i][0][2] = min(dp[i-1][0][2], dp[i-1][1][2]);
dp[i][1][2] = dp[i][1][u];
} else {
dp[i][0][2] = dp[i][0][u];
dp[i][1][2] = min({dp[i-1][1][2], dp[i][1][u], dp[i-1][0][2]+1});
}
}
cout << min(dp[n][0][2], dp[n][1][2]);
}
