#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <climits>

using namespace std;

int main() {
    int N, K;
    cin >> N >> K;
    vector<string> S(N);
    vector<long long> C(N);
    for (int i = 0; i < N; ++i) {
        cin >> S[i] >> C[i];
    }
    
    string JOI(K, 'J');
    JOI += string(K, 'O');
    JOI += string(K, 'I');
    
    long long inf = 1ll<<60;
    vector<long long> dp(3 * K + 1, inf);
    dp[0] = 0;
    
    for (int k0 = 0; k0 <= 3 * K; ++k0) {
        for (int n = 0; n < N; ++n) {
            int k1 = k0;
            for (char s : S[n]) {
                if (k1 < 3 * K && JOI[k1] == s) {
                    ++k1;
                }
            }
            dp[k1] = min(dp[k1], dp[k0] + C[n]);
        }
    }
    
    long long ans = dp[3 * K];
    if (ans == inf) {
        ans = -1;
    }
    
    cout << ans << endl;
    return 0;
}