def check_int(num):
    try:
        int(num)
        return True
    except:
        return False

raw_input()
s = raw_input().split("-")
if len(s) != 2:
    print 'No'
else:
    flag = True
    for i in s:
        if not check_int(i):
            flag = False
    if flag:
        print 'Yes'
    else:
        print 'No'
