new_input=input()
new_input_data= new_input.split(" ")

num_data = int(new_input_data[0])
a_data = int(new_input_data[1])

hikaku = int(num_data*a_data)
counter_d=0

second_input_data = input()
second_input_int= second_input_data.split(" ")

for input_inter in range(num_data):
    counter_d=counter_d+int(second_input_int[input_inter])
    
    
if hikaku==counter_d:
    print("YES")
else:
    print("NO")