#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;

ll dp[300000 + 1];
int k;

char t(int n) {
    if (n < k)
        return 'J';
    else if (n < 2 * k)
        return 'O';
    else
        return 'I';
}

signed main() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    int n;
    cin >> n >> k;
    string s[n];
    ll c[n];
    rep(i, n) {
        cin >> s[i] >> c[i];
    }
    fill(dp, dp + 3 * k + 1, LINF);
    dp[0] = 0;
    rep(i, 3 * k) {
        rep(j, n) {
            int now = 0;
            rep(l, s[j].size()) {
                if (s[j][l] == t(i + now)) {
                    now++;
                    dp[i + now] = min(dp[i + now], dp[i] + c[j]);
                }
            }
        }
    }
    cout << (dp[3 * k] != LINF ? dp[3 * k] : -1) << endl;
    return 0;
}