import java.io.BufferedReader
import java.io.InputStream
import java.io.InputStreamReader
import java.util.*
import kotlin.math.abs
import kotlin.math.max
import kotlin.math.min

data class Entry(val s: String, val c:  Long)
data class Edge(val v: Int, val weight: Long)
val INF = 1e18.toLong()

class Solver(stream: InputStream, private val out: java.io.PrintWriter) {
  fun solve() {
    val N = ni()
    val K = ni()
    val E = Array(N){Entry(ns(), nl())}
    val g = Array(K * 3 + 1) { mutableListOf<Edge>()}
    val JOI = "JOI"

    val cnt = Array(N){i -> Array(3){j -> E[i].s.count{ it == JOI[j]}} }

    fun calcEnd(s: String, start: Int): Int {
      var cur = start
      for (i in 0 until s.length) {
        if (cur == 3 * K) return cur
        if (s[i] == JOI[cur / K]) cur++
      }
      return cur
    }

    for ((i, e) in E.withIndex()) {
      for (s in 0 until 3 * K) {
        val end = if (K - s % K > 100) {
          s + cnt[i][s / K]
        } else {
          calcEnd(e.s, s)
        }
        if (end > s) {
          g[s].add(Edge(end, e.c))
        }
      }
    }

    debug{g.joinToString(" ")}

    val D = LongArray(g.size){INF}
    D[0] = 0
    for (u in 0 until 3 * K) {
      if (D[u] == INF) continue

      for (i in 0 until g[u].size) {
        val e = g[u][i]
        if (D[e.v] > D[u] + e.weight) {
          D[e.v] = D[u] + e.weight
        }
      }
    }
    debug(D)
    val cost = D[3 * K]
    if (cost == INF) out.println(-1) else out.println(cost)
  }













































  private val isDebug = try {
    // なんか本番でエラーでる
    System.getenv("MY_DEBUG") != null
  } catch (t: Throwable) {
    false
  }

  private var tokenizer: StringTokenizer? = null
  private val reader = BufferedReader(InputStreamReader(stream), 32768)
  private fun next(): String {
    while (tokenizer == null || !tokenizer!!.hasMoreTokens()) {
      tokenizer = StringTokenizer(reader.readLine())
    }
    return tokenizer!!.nextToken()
  }

  private fun ni() = next().toInt()
  private fun nl() = next().toLong()
  private fun ns() = next()
  private fun na(n: Int, offset: Int = 0): IntArray {
    return map(n) { ni() + offset }
  }
  private fun nal(n: Int, offset: Int = 0): LongArray {
    val res = LongArray(n)
    for (i in 0 until n) {
      res[i] = nl() + offset
    }
    return res
  }

  private fun na2(n: Int, offset: Int = 0): Array<IntArray> {
    val a  = Array(2){IntArray(n)}
    for (i in 0 until n) {
      for (e in a) {
        e[i] = ni() + offset
      }
    }
    return a
  }

  private inline fun map(n: Int, f: (Int) -> Int): IntArray {
    val res = IntArray(n)
    for (i in 0 until n) {
      res[i] = f(i)
    }
    return res
  }

  private inline fun debug(msg: () -> String) {
    if (isDebug) System.err.println(msg())
  }

  private fun debug(a: LongArray) {
    debug { a.joinToString(" ") }
  }

  private fun debug(a: IntArray) {
    debug { a.joinToString(" ") }
  }

  private fun debug(a: BooleanArray) {
    debug { a.map { if (it) 1 else 0 }.joinToString("") }
  }

  private fun debugDim(A: Array<IntArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }

  /**
   * 勝手にimport消されるのを防ぎたい
   */
  private fun hoge() {
    min(1, 2)
    max(1, 2)
    abs(-10)
  }
}

fun main() {
  val out = java.io.PrintWriter(System.out)
  Solver(System.`in`, out).solve()
  out.flush()
}