#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define lb lower_bound
#define all(a) begin(a),end(a)
const int mxN = (int)2e5+10;
string s, ss;
int n, a[mxN], b[mxN], dp[mxN][3];
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n >> s >> ss; int ans = mxN;
for(int i = 0; i < n; i++)
a[i+1] = s[i]=='1', b[i+1] = ss[i]=='1';
memset(dp,63,sizeof(dp)); dp[0][2] = 0;
for(int i = 1; i <= n; i++){
for(int j = 0; j < 3; j++){
bool eq = ((j==2 and a[i]==b[i]) or j==b[i]);
dp[i][j] = min(dp[i][j], dp[i-1][0]+!b[i-1]*!eq+(j==1));
dp[i][j] = min(dp[i][j], dp[i-1][1]+b[i-1]*!eq+(j==0));
dp[i][j] = min(dp[i][j], dp[i-1][2]+!eq*(a[i-1]==b[i-1])+(j!=2));
if(i==n) ans = min(ans, dp[i][j]);
}
}
cout << ans;
}
