import sequtils,strutils
var
    N = stdin.readline.parseInt
    A : array[500010, bool]
    sosu = newSeq[int](0)
    ans = 0
for i in 2..N:
    if A[i] == false:
        sosu.add(i)
        var j = i * 2
        while j <= N:
            A[j] = true
            j += i

for p in sosu:
    for r in sosu:
        if r * r > 2 * N:
            break
        var q = r * r - p
        if q > 1 and q <= N and A[q] == false:
            ans += 1

echo ans