#include <bits/stdc++.h> using namespace std; #define print(l) for(auto i:l) cout<<i<<" ";cout<<endl; #define input(t,l,n) vector<t>l(n);for(int i = 0;i<n;i++)cin>>l[i]; #define int long long #define pb push_back #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> #define all(l) l.begin(),l.end() #define pii pair<int,int> #define fi first #define se second const int M = 1e9+7; const int inf = 1e18; int bp(int x, int y, int p){ int res = 1; x = x % p; while (y > 0) { if (y & 1) res = (res * x) % p; y = y >> 1; x = (x * x) % p; } return res; } int MI(int n, int p){ return bp(n, p - 2, p); } int mul(int x,int y, int p){ return x * 1ull * y % p; } int di(int x,int y, int p){ return mul(x, MI(y, p), p); } int n , m , k , q,d; void solve(int testcase_number){ cin>>n>>m; string s; cin>>s; vector<int> ind[3]; for(int i = 0;i<n;i++){ if(s[i] == 'J'){ ind[0].pb(i); } else if(s[i] == 'O'){ ind[1].pb(i); } else{ ind[2].pb(i); } } ind[0].pb(inf); ind[1].pb(inf); ind[2].pb(inf); // print(ind[2]); int ans = inf; for(int i =0 ;i+m-1<ind[0].size();i++){ int fj = ind[0][i]; int lj = ind[0][i+m-1]; int t1 = lower_bound(all(ind[1]),lj)-ind[1].begin(); int fo = ind[1][t1]; int lo = ind[1][min((int)ind[1].size()-1,t1+m-1)]; int t = lower_bound(all(ind[2]),lo)-ind[2].begin(); int fi = ind[2][t]; int li = ind[2][min((int)ind[2].size()-1,t+m-1)]; if(li == inf){ continue; } ans = min(ans,li-fj+1 - 3*m); // ans = max(ans,-1ll); // cout<<t1<<" "<<t<<endl; // cout<<ans<<" "<<fj<<" "<<lj<<" "<<fo<<" "<<lo<<" "<<fi<<" "<<li<<endl; } if(ans == inf){ ans = -1; } cout<<ans<<endl; } signed main(){ ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE cin.tie(0), cout.tie(0); cout << fixed<<setprecision(9); int t = 1; // cin>>t; for(int i = 1;i<=t;i++){ solve(i); } }