我的代码是这样的:哪里错了

n=int(input())

lst=input().split() s=0

for i in range(n):

for a in range(i):
    b=int(lst[i])-int(lst[a])
    if str(b) in lst and int(lst[i])!=int(lst[a])*2:
        s+=1
        break

print(s)