#include <bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;
typedef long long ll;
typedef pair<int,int>P;

const int MOD=1000000007;
const int INF=0x3f3f3f3f;
const ll INFL=0x3f3f3f3f3f3f3f3f;

string s[100];
int c[100];
ll dp[320000];

int main(){
	int n,K;cin>>n>>K;
	rep(i,n){
		cin>>s[i]>>c[i];
	}
	memset(dp,0x3f,sizeof(dp));
	dp[0]=0;
	rep(i,3*K){
		if(dp[i]==INFL)continue;
		rep(j,n){
			int cur=i;
			rep(k,s[j].size()){
				char want=(cur<K?'J':(cur<2*K?'O':'I'));
				if(cur<3*K&&s[j][k]==want)cur++;
			}
			dp[cur]=min(dp[cur],dp[i]+c[j]);
		}
	}
	if(dp[3*K]==INFL)puts("-1");
	else cout<<dp[3*K]<<endl;
}