#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr ll INF = 1e17;

inline char target_char(int nexi, int K) {
    if (nexi < K) return 'J';
    if (nexi < 2 * K) return 'O';
    if (nexi < 3 * K) return 'I';
    return '#';
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n, K;
    cin >> n >> K;

    vector<string> s(n);
    vector<ll> c(n);
    for (int i = 0; i < n; ++i) {
        cin >> s[i] >> c[i];
    }

    vector< map<char, int> > cnt(n);
    //vector< map<char, vector<int> > > warp(n);
    for (int i = 0; i < n; ++i) {
        int sz = s[i].size();
        for (int j = 0; j < sz; ++j) {
            ++cnt[i][s[i][j]];
            //warp[i][s[i][j]].push_back(j + 1);
        }
    }

    vector<ll> dp(3 * K + 1, INF);
    dp[0] = 0;
    for (int i = 0; i < 3 * K; ++i) {
        if (dp[i] >= INF) continue;
        for (int j = 0; j < n; ++j) {
            int sz = s[j].size();

            int nexi = i;
            char tar = target_char(nexi, K);
            int lim = (nexi / K + 1) * K; 
            if (cnt[j][tar] + nexi < lim) {
                nexi += cnt[j][tar];
                dp[nexi] = min(dp[nexi], dp[i] + c[j]);
                continue;
            }

            for (char ch : s[j]) {
                tar = target_char(nexi, K);
                nexi += (tar == ch);
            }
            dp[nexi] = min(dp[nexi], dp[i] + c[j]);
        }
    }
    cout << (dp[3 * K] >= INF ? -1 : dp[3 * K]) << "\n";
    return 0;
}