n, m = map(int, input().split())
c = []
s = []
d = {}
d[0] = 0
for _ in range(m):
    si, ci = input().split()
    ci = int(ci)
    c.append(ci)
    si_int = 0
    for j in range(n):
        si_int <<= 1
        if si[j] == "Y":
            si_int |= 1
    s.append(si_int)
    # d[si_int] = ci
for i in range(m):
    dkeys = list(d.keys())
    for t in dkeys:
        if t | s[i] in d.keys():
            d[t | s[i]] = min(d[t | s[i]], d[t] + c[i])
        else:
            d[t | s[i]] = d[t] + c[i]
if 2**n - 1 in d.keys():
    print(d[2**n - 1])
else:
    print(-1)
 

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10 14
YNNYNNNYYN 774472905
YYNNNNNYYY 75967554
NNNNNNNNNN 829389188
NNNNYYNNNN 157257407
YNNYNNYNNN 233604939
NYYNNNNNYY 40099278
NNNNYNNNNN 599672237
NNNYNNNNYY 511018842
NNNYNNYNYN 883299962
NNNNNNNNYN 883093359
NNNNNYNYNY 54742561
NYNNYYYNNY 386272705
NNNNYYNNNN 565075143
NNYNYNNNYN 123300589