#include <bits/stdc++.h> using namespace std; #define int long long signed main(){ ios::sync_with_stdio(false); cin.tie(0); int n, k; cin >> n >> k; string x; cin >> x; vector<int> J; vector<int> O; vector<int> I; for(int i = 0; i < n; i++){ if(x[i] == 'J'){ J.push_back(i); }else if(x[i] == 'O'){ O.push_back(i); }else{ I.push_back(i); } } int mn = 1e18; for(int i = 0; i < n; i++){ //start at i auto itJ = lower_bound(J.begin(), J.end(), i) - J.begin(); itJ += k-1; if(itJ >= J.size()){ continue; } auto itO = lower_bound(O.begin(), O.end(), J[itJ]) - O.begin(); itO += k-1; if(itO >= O.size()){ continue; } auto itI = lower_bound(I.begin(), I.end(), O[itO]) - I.begin(); itI += k-1; if(itI >= I.size()){ continue; } mn = min(mn, I[itI] - i + 1 - 3*k); } if(mn == 1e18){ mn = -1; } cout << mn << "\n"; return 0; }