import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.NoSuchElementException;

public class Main {
	public static void main(String[] args) {
		new Main().run();
	}
	
	void run() {
		FastScanner sc=new FastScanner();
		int N=sc.nextInt();
		int K=sc.nextInt();
		char[][] S=new char[N][];
		long[] C=new long[N];
		int[][] cnt=new int[N][3];
		long[] dp=new long[3*K+1];
		long INF=Long.MAX_VALUE/3;
		Arrays.fill(dp, INF);
		dp[0]=0;
		char[] target=("J".repeat(K)+"O".repeat(K)+"I".repeat(K)).toCharArray();
		char[] JOI= "JOI".toCharArray();
		for (int i=0;i<N;++i) {
			S[i]=sc.next().toCharArray();
			C[i]=sc.nextLong();
			for (char c:S[i]) {
				for (int j=0;j<3;++j) {
					if (c==JOI[j]) ++cnt[i][j];
				}
			}
		}
		// dp[i]=target[i-1]まで揃えたときのコスト
		for (int i=0;i<3*K;++i) {
			for (int j=0;j<N;++j) {
				if (i+100<target.length && target[i]==target[i+100]) {
					dp[i+cnt[j][i/K]]=Math.min(dp[i+cnt[j][i/K]], dp[i]+C[j]);
				} else {
					int p=i;
					for (int k=0;k<S[j].length;++k) {
						if (p<target.length && target[p]==S[j][k]) ++p;
					}
					dp[p]=Math.min(dp[p], dp[i]+C[j]);
				}
			}
		}
		System.out.println(dp[3*K]==INF?-1:dp[3*K]);
	}
	
	void tr(Object...objects) {System.out.println(Arrays.deepToString(objects));}
}




class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;}
    public boolean hasNext() { skipUnprintable(); return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
    	return (int)nextLong();
    }
}