#include <iostream>
#include <vector>
using namespace std;
const int NMAX = 1e6;
const int INF = 1e9;
int dp[NMAX + 1][6];
int Min(vector <int> v){
int mini = INF;
for(int x : v){
mini = min(mini, x);
}
return mini;
}
int main(){
int n;
cin >> n;
string a, b;
cin >> a >> b;
a = "$" + a, b = "$" + b;
for(int i = 0; i <= n; i++){
for(int j = 0; j < 6; j++){
dp[i][j] = INF;
dp[i][j] = INF;
}
}
dp[0][0] = 0;
for(int i = 1; i <= n; i++){
if(a[i] == b[i]){
dp[i][0] = Min({dp[i - 1][0], dp[i - 1][1], dp[i - 1][2], dp[i - 1][3], dp[i - 1][4], dp[i - 1][5]});
}else{
dp[i][3] = Min({dp[i - 1][0] + 1, dp[i - 1][1] + 1, dp[i - 1][2] + 1, dp[i][3], dp[i][4], dp[i][5]});
}
if(b[i] == '0'){
dp[i][1] = Min({dp[i - 1][0] + 1, dp[i - 1][1], dp[i - 1][2] + 1, dp[i - 1][3] + 1, dp[i - 1][4], dp[i - 1][5] + 1});
dp[i][5] = Min({dp[i - 1][0] + 2, dp[i - 1][1] + 2, dp[i - 1][2] + 1, dp[i - 1][3] + 1, dp[i - 1][4] + 1, dp[i - 1][5]});
}else{
dp[i][2] = Min({dp[i - 1][0] + 1, dp[i - 1][1] + 1, dp[i - 1][2], dp[i - 1][3] + 1, dp[i - 1][4] + 1, dp[i - 1][5]});
dp[i][4] = Min({dp[i - 1][0] + 2, dp[i - 1][1] + 1, dp[i - 1][2] + 2, dp[i - 1][3] + 1, dp[i - 1][4], dp[i - 1][5] + 1});
}
}
cout << Min({dp[n][0], dp[n][1], dp[n][2], dp[n][3], dp[n][4], dp[n][5]});
return 0;
}
/*
Notice how op1 & op2 dont overlap, how op3 does not overlap, how op3 comes on top.
0 - nothing
1 - op 1
2 - op 2
3 - op 3
4 - op1 & op3
5 - op2 & op3
*/
