#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define fi first
#define se second
#define eb emplace_back
#define popc __builtin_popcount
#define sgn(x) ((x)&1?-1:1)
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vp;
typedef unsigned long long ull;
typedef long double ld;

int read() {
    int x=0,w=1; char c=getchar(); 
    while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
    while(isdigit(c)) {x=x*10+c-'0'; c=getchar();}
    return x*w;
}

const int N=1e6+9;
int n,f[N][2][3][3],a[N],b[N];
char s[N],t[N];

signed main() {
    n=read();
    scanf("%s%s",s+1,t+1);
    rep(i,1,n) a[i]=(s[i]=='1');
    rep(i,1,n) b[i]=(t[i]=='1');
    memset(f,0x3f,sizeof(f));
    f[0][0][0][0]=0;
    int ans=0x3f3f3f3f;
    rep(i,1,n) rep(j,0,1) rep(k,0,2) rep(l,0,2) {
        bool flag=1;
        if(l==0) {
            if(k==0) {
                if(j==0) flag=(a[i]==b[i]);
                else flag=(a[i]!=b[i]);
            } else if(k==1) {
                flag=(b[i]==0);
            } else {
                flag=(b[i]==1);
            }
        } else if(l==1) {
            flag=(b[i]==0);
        } else {
            flag=(b[i]==1);
        }
        if(!flag) continue;
        rep(j0,0,1) rep(k0,0,2) rep(l0,0,2) {
            int w=(j0==0&&j==1)+(k!=0&&k0!=k)+(l!=0&&l0!=l);
            f[i][j][k][l]=min(f[i][j][k][l],f[i-1][j0][k0][l0]+w);
        }
        if(i==n) ans=min(ans,f[i][j][k][l]);
    }
    printf("%d\n",ans);
    return 0;
}