#include <bits/stdc++.h>
using namespace std;
int n;
string a, b, ch[3];
int dp[1000005][5];
//0 can go to 1(+1) or 3(+1) or 0
//1 can go 2(+1) or 0
//2 can go 1 or 0
//3 can go 4(+1) or 0
//4 can go 3 or 0
int no[5];
int cst[5][5];
//int cst[3][3] = {{2000000, 2000000, 2000000}, {2000000, 2000000, 2000000}, {2000000, 2000000, 2000000}};
int main() {
// your code goes here
cin >> n >> a >> b;
ch[0] = ch[1] = ch[2] = b;
for(int i=0;i<n;i++) {
ch[0][i] = llabs(a[i] - b[i]) + '0';
ch[2][i] = (b[i] == '1' ? '0' : '1');
}
no[0] = 0; no[1] = no[2] = 1; no[3] = no[4] = 2;
for(int i=0;i<5;i++) for(int j=0;j<5;j++) cst[i][j] = 2000000;
cst[0][1] = 1; cst[0][3] = 1; cst[0][0] = 0;
cst[1][2] = 1; cst[1][0] = 0; cst[1][1] = 0;
cst[2][1] = 0; cst[2][0] = 0; cst[2][2] = 0;
cst[3][4] = 1; cst[3][0] = 0; cst[3][3] = 0;
cst[4][3] = 0; cst[4][0] = 0; cst[4][4] = 0;
for(int j=0;j<3;j++) ch[j].insert(ch[j].begin(), '0');
for(int i=0;i<=n;i++) {
for(int j=0;j<5;j++) {
dp[i][j] = 2000000;
}
}
dp[0][0] = 0;
for(int i=0;i<n;i++) {
for(int nn=0;nn<5;nn++) {
for(int nx=0;nx<5;nx++) {
dp[i+1][nx] = min(dp[i+1][nx], dp[i][nn] + cst[nn][nx] + (ch[no[nn]][i] == '0' && '1' == ch[no[nx]][i+1]));
}
}
}
int ans = 2000000;
//for(int i=0;i<=n;i++) {
for(int j=0;j<5;j++) {
//cout << dp[i][j] << ' ';
ans = min(ans, dp[n][j]);
}
//cout << '\n';}
cout << ans;
return 0;
}
