#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>
#define ykh mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define __lg(x) 63-__builtin_clzll(x)
#define pow2(x) (1LL<<x)
void __print(int x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef local
void setio(){freopen("/Users/iantsai/Library/Mobile Documents/com~apple~CloudDocs/cpp/Empty.md","r",stdin);}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
void setio(){}
#define debug(x...)
#endif
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
struct line{
int a,b;
int operator()(const int x)const{
return a*x+b;
}
};
bool check(line l1,line l2,line l3){
return (l3.b-l2.b)*(l1.a-l2.a)<=(l2.b-l1.b)*(l2.a-l3.a);
}
const int mxn=1e6+5;
int dp[mxn][3][2];// [0/1/2]第i位用了on/off [0/1]第i位用了tog
void upd(int i,int l,int r,bool tf=1){
for(int j=0;j<3;j++){
for(int k=0;k<2;k++){
int ad=0;
if(l and l!=j)ad++;
if(r and r!=k)ad++;
chmin(dp[i][l][r],dp[i-1][j][k]+ad);
}
}
}
signed main(){
setio();
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;
memset(dp,0x3f3f3f3f,sizeof(dp));
dp[0][0][0]=0;
for(int i=1;i<=n;i++){
if(a[i]==b[i]){
upd(i,0,0,0);
}
if(a[i]=='0' and b[i]=='0'){
upd(i,1,0);
chmin(dp[i][1][0],min(dp[i-1][1][0],dp[i-1][1][1]));
upd(i,2,1);
}
if(a[i]=='1' and b[i]=='1'){
upd(i,2,0);
chmin(dp[i][2][0],min(dp[i-1][2][0],dp[i-1][2][1]));
upd(i,1,1);
}
if(a[i]=='1' and b[i]=='0'){
upd(i,1,0);
chmin(dp[i][1][0],min(dp[i-1][1][0],dp[i-1][1][1]));
upd(i,0,1);
chmin(dp[i][0][1],min({dp[i-1][0][1],dp[i-1][1][1],dp[i-1][2][1]}));
upd(i,2,1);
}
if(a[i]=='0' and b[i]=='1'){
upd(i,2,0);
chmin(dp[i][2][0],min(dp[i-1][2][0],dp[i-1][2][1]));
upd(i,0,1);
chmin(dp[i][0][1],min({dp[i-1][0][1],dp[i-1][1][1],dp[i-1][2][1]}));
upd(i,1,1);
}
debug(dp[i][0][0],dp[i][0][1],dp[i][1][0],dp[i][1][1],dp[i][2][0],dp[i][2][1]);
}
cout<<min({dp[n][0][0],dp[n][0][1],dp[n][1][0],dp[n][1][1],dp[n][2][0],dp[n][2][1]})<<'\n';
}
/*
input:
*/
