#define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include typedef long long int ll; //#include using namespace std; ll gcd(ll a, ll b) { if (a < b)swap(a, b); if (b == 0)return a; return gcd(b, a % b); } int lcm(int a, int b) { return a * b / gcd(a, b); } long long mod_exp(long long b, long long e, long long m) { if (e > 0 && b == 0) return 0; long long ans = 1; b %= m; while (e > 0) { if ((e & 1LL)) ans = (ans * b) % m; e = e >> 1LL; b = (b * b) % m; } return ans; } int main() { int Q; Q = 1; //cin >> Q; while (Q--) { int n; cin >> n; int p = 0; if (n > 2)p += 2; for (int i = 3; i <= n; i+=2) { bool f = 1; for (int j = 3; j * j <= i; j++) { if (i % j)continue; f = 0; break; } if (f)p += i; } cout << p; } return 0; }