#include<bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
//Don't open the standings during contests.
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
int n;
cin>>n;
string a,b;
cin>>a>>b;
a="#"+a;
b="#"+b;
vector<vector<int>>dp(n+1,vector<int>(6,8e18));
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-1][3],dp[i-1][4],dp[i-1][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<<dp[i][0]<<' '<<dp[i][1]<<' '<<dp[i][2]<<' '<<dp[i][3]<<' '<<dp[i][4]<<' '<<dp[i][5]<<'\n';
}
cout<<min({dp[n][0],dp[n][1],dp[n][2],dp[n][3],dp[n][4],dp[n][5]})<<'\n';
}
/*
input:
0
1 1
2 2
3 3
4 1 3
5 2 3
*/
