#![allow(non_snake_case)]
#![allow(unused_imports)]
//use itertools::Itertools;
//use proconio::input;
//use proconio::marker::*;
use std::cmp::Reverse;
use std::collections::*;

fn main() {
    input! {
        n:usize,
        k:usize,
        sc:[(chars,usize);n],
    }

    let mut cnts = vec![vec![0; 3]; n];
    for i in 0..n {
        for c in sc[i].0.iter() {
            cnts[i][toidx(*c)] += 1;
        }
    }

    const INF: usize = std::usize::MAX;
    let mut dp = vec![INF; 3 * k + 1];
    dp[0] = 0;
    for i in 0..3 * k {
        for j in 0..n {
            if dp[i] == INF {
                continue;
            }
            if i / k != 2 && i + cnts[j][i / k] < i / k * k {
                dp[(i + cnts[j][i / k]).min(3 * k)] =
                    dp[(i + cnts[j][i / k]).min(3 * k)].min(dp[i] + sc[j].1);
            } else {
                let mut l = i;
                for c in sc[j].0.iter() {
                    if toidx(*c) == l / k {
                        l += 1;
                    }
                }

                dp[l.min(3 * k)] = dp[l.min(3 * k)].min(dp[i] + sc[j].1);
            }
        }
    }

    let ans = dp[3 * k];
    if ans == INF {
        println!("-1");
    } else {
        println!("{}", ans);
    }
}

fn toidx(c: char) -> usize {
    match c {
        'J' => 0,
        'O' => 1,
        'I' => 2,
        _ => unreachable!(),
    }
}

mod input{
    #[macro_export]
    macro_rules! input {
        (source = $s:expr, $($r:tt)*) => {
            let mut iter = $s.split_whitespace();
            input_inner!{iter, $($r)*}
        };
        ($($r:tt)*) => {
            let s = {
                use std::io::Read;
                let mut s = String::new();
                std::io::stdin().read_to_string(&mut s).unwrap();
                s
            };
            let mut iter = s.split_whitespace();
            input_inner!{iter, $($r)*}
        };
    }

    #[macro_export]
    macro_rules! input_inner {
        ($iter:expr) => {};
        ($iter:expr, ) => {};

        ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
            let $var = read_value!($iter, $t);
            input_inner!{$iter $($r)*}
        };
    }

    #[macro_export]
    macro_rules! read_value {
        ($iter:expr, ( $($t:tt),* )) => {
            ( $(read_value!($iter, $t)),* )
        };

        ($iter:expr, [ $t:tt ; $len:expr ]) => {
            (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
        };

        ($iter:expr, chars) => {
            read_value!($iter, String).chars().collect::<Vec<char>>()
        };

        ($iter:expr, usize1) => {
            read_value!($iter, usize) - 1
        };

        ($iter:expr, $t:ty) => {
            $iter.next().unwrap().parse::<$t>().expect("Parse error")
        };
    }

}