package contest200417;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class C2 {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		int n = ni(), K = ni();
		char[][] ss = new char[n][];
		int[] cs = new int[n];
		for(int i = 0;i < n;i++){
			ss[i] = ns().toCharArray();
			cs[i] = ni();
		}
		
		char[] s = new char[3*K];
		for(int i = 0;i < K;i++){
			s[i] = 'J';
			s[i+K] = 'O';
			s[i+2*K] = 'I';
		}			
		long[] dp = new long[3*K+1];
		long I = Long.MAX_VALUE / 2;
		Arrays.fill(dp, Long.MAX_VALUE / 2);
		dp[0] = 0;
		int[] setj = new int[n];
		int[] seto = new int[n];
		int[] seti = new int[n];
		Arrays.fill(setj, -1);
		Arrays.fill(seto, -1);
		Arrays.fill(seti, -1);
		for(int i = 0;i < 3*K;i++){
			for(int j = 0;j < n;j++){
				if(i+ss[j].length < 3*K && s[i] == s[i+ss[j].length-1]){
					if(s[i] == 'J' && setj[j] != -1){
						dp[i+setj[j]] = Math.min(dp[i+setj[j]], dp[i] + cs[j]);
						continue;
					}
					if(s[i] == 'O' && seto[j] != -1){
						dp[i+seto[j]] = Math.min(dp[i+seto[j]], dp[i] + cs[j]);
						continue;
					}
					if(s[i] == 'I' && seti[j] != -1){
						dp[i+seti[j]] = Math.min(dp[i+seti[j]], dp[i] + cs[j]);
						continue;
					}
				}
				int p = i;
				for(int k = 0;k < ss[j].length && p < 3*K;k++){
					if(ss[j][k] == s[p]){
						p++;
					}
				}
				if(i+ss[j].length < 3*K && s[i] == s[i+ss[j].length-1]){
					if(s[i] == 'J')setj[j] = p-i;
					if(s[i] == 'O')seto[j] = p-i;
					if(s[i] == 'I')seti[j] = p-i;
				}
				
				dp[p] = Math.min(dp[p], dp[i] + cs[j]);
			}
		}
		long ans = dp[3*K];
		out.println(ans >= I/2 ? -1 : ans);
	}
	
	public static int[] mpTable(char[] str)
	{
		int n = str.length;
		int[] mp = new int[n+1];
		mp[0] = -1;
		for(int i = 1, j = 0;i < n;i++){
			while(j >= 0 && str[i] != str[j])j = mp[j];
			mp[i+1] = ++j;
		}
		return mp;
	}
	
	

	
	void run() throws Exception
	{
//		int n = 2;
//		Random gen = new Random();
//		int K = gen.nextInt(5)+1;
//		StringBuilder sb = new StringBuilder();
//		sb.append(n + " ");
//		sb.append(K + "\n");
//		for (int i = 0; i < n; i++) {
//			int len = gen.nextInt(5)+1;
//			for(int j = 0;j < len;j++){
//				sb.append("JOI".charAt(gen.nextInt(3)));
//			}
//			sb.append(" " + (gen.nextInt(5)+1) + "\n");
//		}
//		INPUT = sb.toString();

		
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new C2().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}