#include<bits/stdc++.h>
using namespace std;
#define int int64_t
#define pb push_back
#define pii pair<int, int>
#define st first
#define nd second
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
int dp[1000009][14];
int dis[14][3] = {
{-1, -1, -1},
{0, -1, -1},
{1, -1, -1},
{2, -1, -1},
{0, 2, -1},
{1, 2, -1},
{2, 0, -1},
{2, 1, -1},
{2, 0, 1},
{0, 2, 1},
{0, 1, 2},
{2, 1, 0},
{1, 2, 0},
{1, 0, 2}
};
int f(int a, int b) {
for(int i=0;i<3;i++) {
if(dis[a][i]!=dis[b][i]) {
for(int j=0;j<4;j++) {
if(j==3||dis[b][j]==-1)
return j-i;
}
}
}
return 0;
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
for(int i=0;i<=n;i++) {
for(int j=0;j<14;j++) {
dp[i][j] = 1e9;
}
}
dp[0][0] = 0;
string A, B;
cin >> A >> B;
//for(int i=0;i<14;i++) {
//for(int j=0;j<14;j++) {
//cout << f(i, j) << " ";
//}
//cout << "\n";
//}
for(int i=1;i<=n;i++) {
for(int j=0;j<14;j++) {
for(int k=0;k<14;k++) {
int New = A[i-1]-'0';
for(int I=0;I<3;I++) {
if(dis[k][I]==0) New = 0;
if(dis[k][I]==1) New = 1;
if(dis[k][I]==2) New = 1-New;
}
if(New!=B[i-1]-'0') continue;
dp[i][k] = min(dp[i][k], dp[i-1][j]+f(j, k));
}
}
//for(int j=0;j<14;j++) {
//cout << i << " " << j << ": " << dp[i][j] << "\n";
//}
}
int ans = 1e9;
for(int i=0;i<=n;i++) {
for(int j=0;j<14;j++) {
ans = min(ans, dp[n][j]);
}
}
cout << ans << "\n";
}
