func main()
	var n: int :: cui@inputInt()
	
	var primes: []int :: #[n]int
	do primes[0] :: 2
	var primesNum: int :: 1
	for i(3, n, 2)
		for j(0, primesNum - 1)
			var prime: int :: primes[j]
			if(prime ^ 2 > i)
				break j
			end if
			if(i % prime = 0)
				skip i
			end if
		end for
		do primes[primesNum] :: i
		do primesNum :+ 1
	end for
	
	var ans: int :: 0
	for i(0, primesNum - 1)
		var r: int :: primes[i]
		if(r * r > 2 * n)
			break i
		end if
		for j(0, primesNum - 1)
			var p: int :: primes[j]
			var q: int :: r * r - p
			if(0 < q & q <= n & math@prime(q))
				do ans :+ 1
			end if
		end for
	end for
	
	do cui@print("\{ans}\n")
end func