#include <bits/stdc++.h>   using namespace std;   const int INF = ~(1 << 31);   const int N = 200000;   int n;   char s[N + 1];   char t[N + 1];   int suffix_array[N + 1];   int *eq;   int lcp[N + 1];   vector<pair<int, int> > lcp_;   inline int add(int a, int b, int md) {     a += b;     if (a >= md) a -= md;     return a;   }   inline int sub(int a, int b, int md) {     a -= b;     if (a < 0) a += md;     return a;   }   int cnt[N + 2];   pair<int, int> res[N + 1];   void count_sort(pair<int, int> *a, int n) {     memset(cnt, 0, 4 * n);     for (int i = 0; i < n; ++i) ++cnt[a[i].first + 1];     for (int i = 1; i <= n; ++i) cnt[i] += cnt[i - 1];     for (int i = 0; i < n; ++i) {       res[cnt[a[i].first]] = a[i];       ++cnt[a[i].first];     }     for (int i = 0; i < n; ++i) a[i] = res[i];   }   pair<int, int> substr[N + 1];   int eq_c1[N + 1], eq_c2[N + 1];   int *suffix_array_build(char *s, int n, int *suffix_array) {     for (int i = 0; i < n; ++i) substr[i] = make_pair((int)s[i], i);     sort(substr, substr + n);     int *eq = eq_c1;     int *eqnw = eq_c2;     eq[substr[0].second] = 0;     for (int i = 1; i < n; ++i)       eq[substr[i].second] =           eq[substr[i - 1].second] + (substr[i].first != substr[i - 1].first);     for (int i = 1; i < n; i <<= 1) {       for (int j = 0; j < n; ++j)         substr[j] = make_pair(eq[sub(substr[j].second, i, n)],                               sub(substr[j].second, i, n));       count_sort(substr, n);       eqnw[substr[0].second] = 0;       for (int j = 1; j < n; ++j)         eqnw[substr[j].second] = eqnw[substr[j - 1].second] +                                  (substr[j].first != substr[j - 1].first ||                                   eq[add(substr[j].second, i, n)] !=                                       eq[add(substr[j - 1].second, i, n)]);       swap(eq, eqnw);     }     for (int i = 0; i < n; ++i) suffix_array[i] = substr[i].second;     return eq;   }   void lcp_build(char *s, int n, int *suffix_array, int *eq, int *lcp) {     for (int i = 0; i < n - 1; ++i) {       while (s[i + lcp[eq[i]]] == s[suffix_array[eq[i] - 1] + lcp[eq[i]]])         ++lcp[eq[i]];       lcp[eq[i + 1]] = max(lcp[eq[i]] - 1, 0);     }   }   void erase_forb() {     int mn = INF;     for (int i = 0; i < n; ++i) {       mn = min(mn, lcp[i]);       if (t[suffix_array[i]] ==  0 ) {         lcp_.push_back(make_pair(suffix_array[i], mn));         mn = INF;       }     }   }   long long calc() {     vector<pair<int, int> > st;     st.push_back(make_pair(0, 0));     long long ans = 0;     for (int i = 0; i < lcp_.size(); ++i) {       ans = max(ans, (long long)n - lcp_[i].first - 1);       while (!st.empty() && lcp_[i].second <= st.back().second) st.pop_back();       ans = max(ans, (long long)(lcp_[i].second * (i - st.back().first + 1)));       st.push_back(make_pair(i, lcp_[i].second));     }     for (int i = 0; i < st.size() - 1; ++i)       ans = max(ans, (long long)(lcp_.size() - st[i].first) * (st[i + 1].second));     return ans;   }   int main() {     scanf( %d%s%s , &n, s, t);     reverse(s, s + n);     reverse(t, t + n);     ++n;     eq = suffix_array_build(s, n, suffix_array);     lcp_build(s, n, suffix_array, eq, lcp);     erase_forb();     printf( %lld n , calc());     return 0;   }