#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("inline")
#include <bits/stdc++.h>
using namespace std;
#define kien long long
#define pb push_back
#define FOR(i, a, b) for (int i = a;i <= b; i++)
#define FORD(i, a, b) for (int i = a;i >= b; i--)
#define pii pair<int, int>
#define fi first
#define se second
#define dembit(a) __builtin_popcountll(a)
#define task "a"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".out","w",stdout)
#define debug(x) cout << x << " ";
#define down cout << "\n"
const kien mod = 1e9 + 7;
const int NTEST = 100;
const int Million = 1e6 + 5;
const int mxn = 1e5 + 5;
mt19937 rd(chrono::high_resolution_clock::now().time_since_epoch().count());
kien rand(kien l, kien r) {
assert(l <= r);
return uniform_int_distribution<kien>(l, r)(rd);
}
kien n, k, m, dem, u, v;
kien maxx, minn, vtr, l, r, ans, dp[mxn][6];
void solve() {
cin >> n;
string a, b;
// cin >> a >> b;
FOR (i, 1, n) cin >> a[i];
FOR (i, 1, n) cin >> b[i];
memset(dp, mod, sizeof dp);
dp[0][0] = 0;
FOR (i, 1, n) FOR (j, 0, 2) FOR (k, 0, 2) {
if (j + k == 3) continue;
/// (j > 0 and k == 0) là khởi đầu một đoạn mới.
dp[i][j] = min(dp[i][j], dp[i - 1][k] + (j > 0 and k == 0) + ((i == 1 || (k == 0 ? a[i - 1] : k + 47) == b[i - 1] and (j == 0 ? a[i] : j + 47) != b[i])));
}
cout << min(dp[n][0], min(dp[n][1], dp[n][2]));
}
main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
if (fopen(task".inp", "r")) {
fin(task); fou(task);
}
int t = 1; //cin >> t;
while(t--) solve();
cerr << "\n" << 1.0 * clock() / CLOCKS_PER_SEC << "s ";
}
