#include <bits/stdc++.h> #define gc ch = getchar() using namespace std; template <class T> void read(T &s) { s = 0; T f = 1; char gc; while (ch < '0' || ch > '9') { if (ch == '-') f = -1; gc; } while (ch >= '0' && ch <= '9') { s = s * 10 + ch - '0'; gc; } s *= f; } template <class T> void put(T s) { if (s < 0) putchar('-'), s = -s; if (s > 9) put(s / 10); putchar(s % 10 + '0'); } int n, ans, a[200005]; string str; int flag[30]; bool judge(int i) { return str[i] == str[i + 1] && str[i] == str[i + 2]; } int main() { read(n); int op, num = 0, left = -1, right = -1; cin >> str; for (int i = 0; i < n; ++i) { if (i + 2 >= n) break; if (i != 0 && left != -1) { if (str[i] != str[i - 1]) { op = (str[i] - 'a') + 1; if (judge(i)) { if (flag[op]) { if (i - left > ans * 3) ans = (i - left) / 3; left += flag[op] * 3; num -= flag[op]; for (int j = 1; j < 30; ++j) { if (flag[j] >= flag[op]) flag[j] -= flag[op]; else flag[j] = 0; } flag[op] = ++num; i += 2; right = i + 1; continue; } else { flag[op] = ++num; i += 2; right = i + 1; continue; } } else { if (i - left > ans * 3) ans = (i - left) / 3; for (int j = 1; j < 27; ++j) flag[j] = 0; right = left = -1; num = 0; continue; } } else { if (i - left > ans * 3) ans = (i - left) / 3; for (int j = 1; j < 27; ++j) flag[j] = 0; left = i - 2; num = 0; flag[op] = ++num; right = i + 1; continue; } } else if (judge(i)) { op = (str[i] - 'a') + 1; left = i; flag[op] = ++num; i += 2; right = i + 1; continue; } } if (left != -1) if (right - left > ans * 3) ans = (right - left) / 3; put(ans); }