//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
int main() {_
int n;
cin>>n;
string a,b;
cin>>a>>b;
a="."+a;
b="."+b;
vector<vector<int>> dp(n+1,vector<int>(6,1e9));
//0 nothing
//1 1
//2 2
//3 3
//4 1->3
//5 2->3
//6 min of above
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]});
}
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});
}
if(b[i]=='1'){
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]});
}
if(a[i]!=b[i]){
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]=='1'){
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});
}
if(b[i]=='0'){
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]});
}
}
int ans=1e9;
for(int i=0;i<6;i++){
ans=min(ans,dp[n][i]);
}
cout<<ans<<'\n';
return 0;
}
//maybe its multiset not set
