import sys
input = sys.stdin.readline

N,K=map(int,input().split())

S=[input().split() for i in range(N)]

DP=[1<<63]*(K+2+100)
DP[0]=0

T="J"*K+"O"*K+"I"*K

for i in range(len(T)):
    NEXT=T[i:i+80]

    for j in range(N):
        ind=0
        M=int(S[j][1])
        for s in S[j][0]:
            if ind<len(NEXT) and s==NEXT[ind]:
                ind+=1
                DP[i+ind]=min(DP[i+ind],DP[i]+M)

if 1<<63==DP[K*3]:
    print(-1)
else:
    print(DP[K*3])