#define DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
char A[1000001],B[1000001];
int dp[1000001][3][2];
int main() {
int N;
scanf("%d %s %s",&N,A,B);
int i,j,k,l,m;
dp[0][0][0] = 0,dp[0][0][1] = dp[0][1][0] = dp[0][2][0] = 1,dp[0][1][1] = dp[0][2][1] = 2;
for (i = 0; i < N; i++) {
dp[i+1][0][0] = (A[i] == B[i]) ? dp[i][0][0]:1e9;
dp[i+1][0][1] = (A[i] != B[i]) ? dp[i][0][1]:1e9;
dp[i+1][1][0] = (B[i] == '1') ? dp[i][1][0]:1e9;
dp[i+1][1][1] = (B[i] == '0') ? dp[i][1][1]:1e9;
dp[i+1][2][0] = (B[i] == '0') ? dp[i][2][0]:1e9;
dp[i+1][2][1] = (B[i] == '1') ? dp[i][2][1]:1e9;
for (j = 0; j < 3; j++) {
for (k = 0; k < 2; k++) {
for (l = 0; l < 3; l++) {
for (m = 0; m < 2; m++) {
int c = 0;
if ((j != l) && (j != 0)) c++;
if ((k != m) && (k != 0)) c++;
dp[i+1][j][k] = min(dp[i+1][j][k],dp[i+1][l][m]+c);
}
}
}
}
}
int ans = 1e9;
for (i = 0; i < 3; i++) {
for (j = 0; j < 2; j++) ans = min(ans,dp[N][i][j]);
}
printf("%d\n",ans);
return 0;
}
