#include <bits/stdc++.h> using namespace std; const int INF = 1e9; int n, k; string s; vector<int> J, O, I; bool check(int mid, int idx, vector<int>& v) { return v[mid] > idx; } int Bsearch(int l, int r, vector<int>& v, int idx) { while(l < r) { int mid = (l + r) / 2; bool ok = check(mid, idx, v); if(ok) r = mid; else l = mid + 1; } // cout << "Bsearch : " << l << '\n'; return l; } int main() { cin.tie(NULL)->sync_with_stdio(false); cin >> n >> k >> s; for(int i=0;i<s.size();i++) { if(s[i] == 'J') J.push_back(i); if(s[i] == 'O') O.push_back(i); if(s[i] == 'I') I.push_back(i); } // for(int i=0;i<n;i++) cout << i; cout << '\n'; int res = INF; for(int i=k-1;i<J.size();i++) { if(O.size() <= 0 || I.size() <= 0) continue; int end_J = i; int start_J = i - k + 1; int start_O = Bsearch(0, O.size() - 1, O, J[end_J]); int end_O = start_O + k - 1; int start_I = Bsearch(0, I.size() - 1, I, O[end_O]); int end_I = start_I + k - 1; if(O[start_O] < J[end_J] || I[start_I] < O[end_O] || end_O < start_O || end_I < start_I) continue; // cout << "J : " << J[end_J] << ' ' << J[start_J] << '\n'; // cout << "O : " << O[end_O] << ' ' << O[start_O] << '\n'; // cout << "I : " << I[end_I] << ' ' << I[start_I] << '\n'; // cout << '\n'; int sum = ((I[end_I] - J[start_J] + 1) - (3 * k)) ; res = min(res, sum); } cout << (res == INF ? -1 : res); return 0; }