N,K=map(int,input().split())
S,C=[],[]
for i in range(N):
    s,c=input().split()
    c=int(c)
    S.append(s)
    C.append(c)
JOI="J"*K+"O"*K+"I"*K
inf=1<<60
dp=[inf]*(3*K+1)
dp[0]=0
for k0 in range(3*K+1):
    for n in range(N):
        k1=k0
        for s in S[n]:
            if k1<3*K and JOI[k1]==s:
                k1+=1
        dp[k1]=min(dp[k1],dp[k0]+C[n])
ans=dp[3*K]
if ans==inf:
    ans=-1
print(ans)