#include<bits/stdc++.h>
using namespace std;
#define foru(i,a,b) for(int i=(a); i<=(b); ++i)
#define ford(i,a,b) for(int i=(a); i>=(b); --i)
#define rep(i,a) for(int i=0; i<(a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(),(a).end()
#define bit(s,i) (((s)>>(i))&1)
#define ii pair<int,int>
#define vi vector<int>
#define vii vector<ii>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll
#define _ << " " <<
template <class X, class Y> bool maxi(X &x, Y y){return x<y?x=y,true:false;}
template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;}
const int N=1e6+5;
int n,dp[N][3][2];
string A,B;
void solve(){
cin>>n>>A>>B;
memset(dp,0x3f,sizeof(dp));
dp[0][0][0]=0;
foru(i,0,n-1){
rep(as,3) rep(tog,2){
mini(dp[i][as][tog], dp[i][0][tog]+1);
mini(dp[i][as][tog], dp[i][as][0]+1);
}
rep(as,3) rep(tog,2){
mini(dp[i][0][tog],dp[i][as][tog]);
mini(dp[i][as][0], dp[i][as][tog]);
}
rep(as,3) rep(tog,2){
int st=A[i]-'0';
if(as>0) st=as-1;
if(tog==1) st^=1;
if(st==B[i]-'0') mini(dp[i+1][as][tog],dp[i][as][tog]);
}
}
int res=1e9;
rep(as,3) rep(tog,2) mini(res,dp[n][as][tog]);
cout<<res<<'\n';
}
int32_t main(){
#define task "test"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin.tie(0)->sync_with_stdio(0);
int tc=1; //cin>>tc;
foru(i,1,tc){
solve();
}
}
