def fib (n, memo = {}):
	if (n in memo):
		return memo[n]
	if (n <= 2):
		return 1
	memo[n] = fib(n-1 , memo ) + fib(n-2, memo)
	return memo[n]

print(fib(6))
print(fib(7))
print(fib(8))
print(fib(50))