#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define ALL(v) (v).begin(), (v).end()
using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e18;
constexpr long long MOD = 1e9 + 7;

signed main() {
    int n, k;
    cin >> n >> k;
    string s[n];
    ll c[n];
    rep(i, n) {
        cin >> s[i] >> c[i];
    }
    map<string, ll> mp;
    rep(i, n) {
        rep(j, s[i].size() + 1) {
            for (int k = j; k < s[i].size() + 1; k++){
                string t;
                rep(l, j) {
                    if (s[i][l] == 'J') t.push_back('J');
                }
                if (k == j) goto fin;
                for (int l = j; l < k; l++) {
                    if (s[i][l] == 'O') t.push_back('O');
                }
                for (int l = k; l < s[i].size(); l++) {
                    if (s[i][l] == 'I') t.push_back('I');
                }
            fin:;
                if(mp.count(t)){
                    mp[t] = min(mp[t], c[i]);
                }else{
                    mp[t] = c[i];
                }
            }
        }
    }
    string t;
    rep(i, k) {
        t.push_back('J');
    }
    rep(i, k) {
        t.push_back('O');
    }
    rep(i, k) {
        t.push_back('I');
    }
    ll dp[3 * k + 1];
    fill(dp, dp + 3 * k + 1, LINF);
    dp[0] = 0;
    rep(i, 3 * k) {
        for (int j = 1; j <= 80; j++) {
            if (i + j > 3 * k) continue;
            if (mp.count(t.substr(i, j)))
                dp[i + j] = min(dp[i + j], dp[i] + mp[t.substr(i, j)]);
        }
    }
    cout << (dp[3 * k] != LINF ? dp[3 * k] : - 1)<< endl;
    return 0;
}