A, B = map(int,input().split())
S = list(input())
ans = True
if len(S) != (A+B+1):
    ans = False
elif S.count("-") != 1:
    ans = False
elif S.index("-") != A:
    ans = False
elif S != [i for i in S if i.isdecimal() or i == "-"]:
    ans = False
print(ans)
