#include <bits/stdc++.h>
using namespace std;

#define int long long
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

string s[100];
int rui[100][100][3] = {};

int n, k;

int tmp[300];

string rtmp = "JOI";
int memo[3][100010];

int c[300];

int dp(int cnt, int num){
	if(memo[cnt][num] != -1) return memo[cnt][num];

	int ans = LLONG_MAX;
	for(int i = 0;i < n;i++){
		int nn = s[i].size();
		if(rui[i][nn][cnt] == 0) continue;
		if(num+rui[i][nn][cnt] < k){
			ans = min(ans, dp(cnt, num+rui[i][s[i].size()][cnt])+c[i]);
		}else{
			bool f= false;
			int tnum = num;
			int tcnt = cnt;
			for(int j = 0;j < nn;j++){
				if(s[i][j] == rtmp[tcnt]){
					tnum++;
					if(tnum == k){
						tnum = 0;
						tcnt++;
						if(tcnt == 3){
							ans = min(ans, c[i]);
							f = true;
							break;
						}
					}
				}
			}
			if(!f) ans = min(ans, dp(tcnt, tnum)+c[i]);
		}
	}
	return memo[cnt][num] = ans;
}

signed main(){
	cin >> n >> k;

	tmp['J'] = 0;
	tmp['O'] = 1;
	tmp['I'] = 2;
	
	bool flag[300];

	for(int i = 0;i < n;i++){
		cin >> s[i] >> c[i];
		for(int j = 0;j < s[i].size();j++){
			rui[i][j+1][tmp[s[i][j]]]++;
			rui[i][j+1][0] += rui[i][j][0]; 
			rui[i][j+1][1] += rui[i][j][1]; 
			rui[i][j+1][2] += rui[i][j][2]; 
			flag[s[i][j]] = true;
		}
	}

	if(!(flag['J'] && flag['O'] && flag['I'])){
		cout << -1 << endl;
		return 0;
	}
	memset(memo, -1, sizeof(memo));

	cout << dp(0, 0) << endl;

	return 0;
}