Peli

#include <bits/stdc++.h>
using namespace std;

#define F first
#define S second
#define pb push_back
#define vc vector
#define rep(i, a, b) for (int i = a; i < b; ++i)
#define tra(a, x) for (auto &a : x)
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()

template <typename... T> void get(T &...args) { ((cin >> args), ...); }
template <typename... T> void pri(T &&...args) { ((cout << args << " "), ...); }
template <typename... T> void pril(T &&...args) {
  ((cout << args << " "), ...);
  cout << '\n';
}

using ll = long long;
using vi = vc<int>;
using vll = vc<ll>;
using pi = pair<int, int>;

const ll LINF = 1e18;
const int INF = 1e9;
const ll mod = 1e9 + 7;
const int N = 1e6 + 1;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);

  int n, k;
  get(n, k);

  string s;
  get(s);

  if (k < 3) {
    pril(0);
    return 0;
  }

  int ans = 0;
  set<char> ss;
  for (int i = 0; i < n; ++i) {
    if (ss.count(s[i]) == 0) {
      ss.insert(s[i]);
    }
    if (ss.size() == 3) {
      ++ans;
      ss.clear();
    }
  }
  pril(ans);
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: WRONG ANSWER

Test 3

Group: 3

Verdict: WRONG ANSWER

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED