#include <bits/stdc++.h> #define int long long #define pb push_back using namespace std; const int N=2e5+10; const int inf=1e18; const int mod=1e9+7; vector<int>j,o,i; signed main() { ios_base::sync_with_stdio(NULL); cin.tie(NULL); int T=1; // cin>>T; while(T--) { int n,k; cin>>n>>k; string s; cin>>s; for(int it=0;it<n;it++) { if(s[it]=='J') j.pb(it); if(s[it]=='O') o.pb(it); if(s[it]=='I') i.pb(it); } int ans=inf; for(int it=0;it<=j.size()-k;it++) { int cur=j[it]; int p=upper_bound(o.begin(),o.end(),j[it+k-1])-o.begin()+k-1; if(p>o.size()-1) continue; p=upper_bound(i.begin(),i.end(),o[p])-i.begin()+k-1; if(p>i.size()-1) continue; // cout<<it<<' '; cur+=n-1-i[p]; ans=min(ans,cur); } if(ans==inf) cout<<"-1\n"; else cout<<ans<<' '; } }