#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define repr(i, n) for (int i = (n) - 1; i >= 0; i--)
#define range(a) a.begin(), a.end()

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int N, K; cin >> N >> K;
  vector<ll> dp(3 * K + 1, LLONG_MAX);
  dp[0] = 0;
  vector<string> S(N);
  vector<ll> C(N);
  rep(i, N) cin >> S[i] >> C[i];
  rep(i, 3 * K) if (dp[i] != LLONG_MAX) {
    rep(j, N) {
      int l = i;
      for (char c : S[j]) {
        if (l < K) {
          if (c == 'J') l++;
        } else if (l < 2 * K) {
          if (c == 'O') l++;
        } else if (l < 3 * K) {
          if (c == 'I') l++;
        }
      }
      dp[l] = min(dp[l], dp[i] + C[j]);
    }
  }
  if (dp[3 * K] == LLONG_MAX) {
    cout << -1 << endl;
  } else {
    cout << dp[3 * K] << endl;
  }
}