#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <cstring>
int x;
std::string str[2];
int dp[1000005][3][3];
int sol(int pos, int last_xor, int last_op) {
if (pos==x) {
return 0;
}
if (dp[pos][last_xor][last_op]!=-1) {
return dp[pos][last_xor][last_op];
}
int& ret = (dp[pos][last_xor][last_op] = 0x3f3f3f3f);
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 3; j++) {
int cost = 0;
if (last_xor!=i&&i>0) {
++cost;
}
if (last_op!=j&&j>0) {
++cost;
}
int this_bit = ((j>0) ? (j-1) : (str[0][pos]-'0'));
this_bit ^= i;
if (this_bit == str[1][pos]-'0') {
ret = std::min(ret, sol(pos+1,i,j)+cost);
}
}
}
return ret;
}
int main() {
std::cin >> x >> str[0] >> str[1];
memset(dp,-1,sizeof(dp));
std::cout << sol(0,0,0) << "\n";
}
