# 1. Check If A Number Belongs To The Fibonacci Sequence
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n=int(input("Enter the number: "))
c=0
a=1
b=1
if n==0 or n==1:
    print("Yes")
else:
    while c < n:
        c=a+b
        b=a
        a=c
    if c==n:
        print("Yes")
    else:
        print("No")


output
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Enter the number: 3
Yes

Enter the number: 10
No