判断序列是否为等比数列（避免除法，用乘法判断）
n = int(input())
a = list(map(int,input().split()))
ok = True
for i in range(n-2):
if __①__:
ok = False
print("Yes" if ok else "No")
a[i]*a[i+2] != a[i+1]*a[i+1]
a[i]+a[i+2] != 2*a[i+1]
a[i+1]//a[i] != a[i+2]//a[i+1]
a[i]*a[i+1] != a[i+1]*a[i+2]