#include<bits/stdc++.h>
using namespace std;
constexpr int maxn = 1e6+10;
bool mark[maxn];
string a, b;
int dp[3][2], new_dp[3][2];
// 0 -> melhor com fim preto
// 1 -> fim branco
// 2 -> fim sem fazer nd
// segundo item da dp
// 0 -> termina normal
// 1 -> termina reversed
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int n; cin >> n;
cin >> a >> b;
dp[0][0] = dp[0][1] = dp[1][0] = dp[1][1] = dp[2][1] = n;
auto check = [](int i, char val) {
return (b[i] == val && (i==0||b[i-1]!=val));
};
auto check2 = [](int i, char val) {
return (b[i] == val);
};
auto check3 = [](int i) {
return (a[i] != b[i] && (i==0||a[i-1]==b[i-1]));
};
for(int i = 0; i < n; i++) {
new_dp[0][0] = min(dp[0][0],dp[0][1])+check(i, '1');
new_dp[0][0] = min(new_dp[0][0], min({dp[1][0], dp[1][1], dp[2][0], dp[2][1]}) + 1 + check2(i, '1'));
new_dp[0][1] = dp[0][1]+check(i, '1');
new_dp[0][1] = min(new_dp[0][1], min(dp[1][1], dp[2][1]) + 1 + check2(i, '1'));
new_dp[1][0] = min(dp[1][0],dp[1][1])+check(i, '0');
new_dp[1][0] = min(new_dp[1][0], min({dp[0][0], dp[0][1], dp[2][0], dp[2][1]}) + 1 + check2(i, '0'));
new_dp[1][1] = dp[1][1]+check(i, '0');
new_dp[1][1] = min(new_dp[1][1], min(dp[0][1], dp[2][1]) + 1 + check2(i, '0'));
if(a[i] != b[i])
new_dp[2][0] = n; // inf
else new_dp[2][0] = min({dp[0][0], dp[1][0], dp[2][0], dp[0][1], dp[1][1], dp[2][1]});
if(a[i] == b[i])
new_dp[2][1] = n; // inf
else new_dp[2][1] = min({dp[0][0]+1, dp[1][0]+1, dp[2][0]+1, dp[0][1], dp[1][1], dp[2][1]});
for(int x = 0; x < 3; x++) for(int y = 0; y < 2; y++) swap(new_dp[x][y], dp[x][y]);
}
printf("%d\n", min({dp[0][0], dp[1][0], dp[2][0], dp[0][1], dp[1][1], dp[2][1]}));
}
