#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];
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n >> s >> ss;
for(int i = 0; i < n; i++)
a[i+1] = s[i]=='1', b[i+1] = ss[i]=='1';
for(int i = 1; i <= n; i++){
bool z=1, o=1, x=1, y = 1; dp[i]=i;
for(int j = i; j>=1; j--){
z&=!b[j], o&=b[j], x&=a[j]^b[j], y&=a[j]^!b[j];
if(z or o or x) dp[i] = min(dp[i], dp[j-1]+1);
if(y) dp[i] = min(dp[i], dp[j-1]);
}
}
int ans = dp[n];
for(int i = 1; i <= n; i++) a[i]^=1;
for(int i = 1; i <= n; i++){
bool z=1, o=1, x=1, y = 1; dp[i]=i;
for(int j = i; j>=1; j--){
z&=!b[j], o&=b[j], x&=a[j]^b[j], y&=a[j]^!b[j];
if(z or o or x) dp[i] = min(dp[i], dp[j-1]+1);
if(y) dp[i] = min(dp[i], dp[j-1]);
}
}
cout << min(dp[n]+1,ans);
}
