#include<bits/stdc++.h> using namespace std; const int MAXN = 2e5 + 5; #define int long long int n, k; string s; int pre[MAXN][3]; int ans = INT_MAX; int findd(int t, int pos) { int l = pos; int r = n; int ans = -1; while(l <= r) { int m = (l + r) / 2; if (pre[m][t] - pre[pos - 1][t] >= k) { ans = m; r = m - 1; } else { l = m + 1; } } return ans; } signed main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); cin >> n >> k; cin >> s; s = "%" + s; for (int i = 1; i <= n; i++) { for (int j = 0; j <= 2; j++) { pre[i][j] = pre[i - 1][j]; } if (s[i] == 'J') { pre[i][0]++; } else if (s[i] == 'O') { pre[i][1]++; } else if (s[i] == 'I') { pre[i][2]++; } } for (int i = 1; i <= n; i++) { int l = i; int cur = i; int nxt = findd(0, cur); if (nxt == -1) { continue; } cur = nxt + 1; nxt = findd(1, cur); if (nxt == -1) { continue; } cur = nxt + 1; nxt = findd(2, cur); if (nxt == -1) { continue; } int r = nxt; ans = min(ans, r - l + 1 - 3 * k); } if (ans == INT_MAX) { cout << -1; } else { cout << ans; } }