/*** author: yuji9511 ***/
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using lpair = pair<ll, ll>;
const ll MOD = 1e9+7;
const ll INF = 1e18;
#define rep(i,m,n) for(ll i=(m);i<(n);i++)
#define rrep(i,m,n) for(ll i=(m);i>=(n);i--)
#define printa(x,n) for(ll i=0;i<n;i++){cout<<(x[i])<<" \n"[i==n-1];};
void print() {}
template <class H,class... T>
void print(H&& h, T&&... t){cout<<h<<" \n"[sizeof...(t)==0];print(forward<T>(t)...);}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll N,K;
    cin >> N >> K;
    string S[85];
    ll C[85];
    rep(i,0,N) cin >> S[i] >> C[i];
    ll dp[300010] = {};
    rep(i,0,3*K+1) dp[i] = INF;
    string T = "";
    T += string(K, 'J');
    T += string(K, 'O');
    T += string(K, 'I');
    dp[0] = 0;
    rep(i,0,3*K+1){
        rep(j,0,N){
            ll idx = i;
            ll cnt = 0;
            rep(k,0,S[j].size()){
                if(idx >= 3*K) break;
                if(T[idx] == S[j][k]){
                    cnt++;
                    idx++;
                }else{
                }
            }
            dp[i+cnt] = min(dp[i+cnt], dp[i] + C[j]);
        }
    }
    if(dp[3*K] == INF){
        print(-1);
    }else{
        print(dp[3*K]);
    }
    

}