def make_prime_numbers(n): ''' n以下の素数を列挙したリストを出力する 計算量:O(NloglogN) 入出力例:30 -> [2, 3, 5, 7, 11, 13, 17, 19, 23, 29] ''' is_prime = [True]*(n+1) is_prime[0] = False is_prime[1] = False for i in range(2, int(n**0.5) + 1): if not is_prime[i]: continue for j in range(2 * i, n + 1, i): is_prime[j] = False prime_numbers = [i for i in range(n + 1) if is_prime[i]] return prime_numbers def solve(a, b): res = (a + b)**0.5 return res == int(res) n = int(input()) prime_list = make_prime_numbers(n) memo = {} for i in prime_list: memo[i] = 1 print(len(prime_list)) cnt = 0 for r in range(len(prime_list)): if prime_list[r] **2 > 2 * prime_list[-1]: break for p in range(len(prime_list)): q = prime_list[r]**2 - prime_list[p] if q < 0: break if q in memo : cnt += 1 print(cnt)