// #include <bits/stdc++.h> #include <iostream> #include <cmath> #include <algorithm> #include <map> #include <unordered_map> #include <vector> #include <iomanip> #include <string> #include <queue> #include <set> #include <deque> using namespace std; #define int long long #define endl "\n" #define fi first #define se second const int M=1203465797; const int inf = 1e14; const int LOG=18; const int N=50+5; int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r; int cn[3]; void solve(){ cin >> n >> k; string s; cin >> s; int j=0; string o="JOI"; for (int i=0;i<n;i++){ if (s[i]==o[j]){ cn[j]++; if (cn[j]==k){ j++; } } if (j==3)break; } if (j<3){ cout << -1 << endl; return; } vector<vector<int>>cnt(n+1,vector<int>(3)); s='I'+s; for (int i=1;i<=n;i++){ for (int j=0;j<3;j++){ if (s[i]==o[j])cnt[i][j]++; cnt[i][j]+=cnt[i-1][j]; } } int i=0; j=1; int ans=n; while (j<=n){ if (cnt[j][1]-cnt[i][1]<k){ j++; } else{ int l=0; int h=i-1; int m=(l+h+1)/2; while (l<h){ if (cnt[i][0]-cnt[m][0]<k){ h=m-1; } else{ l=m; } m=(l+h+1)/2; } int li=j+1; int hi=n; int mi=(li+hi)/2; while (li<hi){ if (cnt[mi][2]-cnt[j][2]<k){ li=mi+1; } else{ hi=mi; } mi=(li+hi)/2; } if (cnt[i][0]-cnt[m][0]>=k and cnt[mi][2]-cnt[j][2]>=k){ ans=min(ans,mi-m-3*k); } i++; } } cout << ans << endl; } signed main() { ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE cout << fixed << setprecision(9); srand(time(0)); // int t=1; // cin >> t; for (int _=1;_<=t;_++){ solve(); q++; } }