A, B = map(int, input().split())
S = input()

count = 0
S_list = []
for s in S:
    S_list.append(s)
    if s == '-':
        pass
    else:
        count += 1

hy_count = S_list.count('-')

if count == len(S) - 1 and hy_count == 1:
    print('Yes')
else:
    print('No')
    	