#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define DEBUG(...)
#endif

template <class T> constexpr T inf = numeric_limits<T>::max() / 2.1;

auto chmin = [](auto&& a, auto b) { return b < a ? a = b, 1 : 0; };

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int n, k;
  cin >> n >> k;
  string t = string(k, 'J') + string(k, 'O') + string(k, 'I');
  int m = t.size();
  vector dp(m + 1, inf<long long>);
  dp[m] = 0;
  vector<string> s(n);
  vector<int> cost(n);
  for (int i = 0; i < n; ++i) {
    cin >> s[i] >> cost[i];
  }
  for (int j = m; j--; ) {
    for (int i = 0; i < n; ++i) {
      int ptr = j;
      for (char c : s[i]) {
        if (ptr < m) {
          ptr += c == t[ptr];
        }
      }
      chmin(dp[j], cost[i] + dp[ptr]);
    }
  }
  if (dp[0] >= inf<long long>) {
    dp[0] = -1;
  }
  cout << dp[0] << '\n';
}