Sum

input/code.cpp: In function 'int is_prime(int)':
input/code.cpp:50:25: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
     if (n <= 1 || n > 3 && (n % 2 == 0 || n % 3 == 0))
                   ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/****Author: Barish Namazov****/
#include <bits/stdc++.h>

using namespace std;

/***TEMPLATE***/
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()

#define F first
#define S second
#define pb push_back

#define endl '\n'

const int max4 = 10004;
const int maxx = 100005;
const int max6 = 1000006;
const int lg5 = 17;

const int INF = 2 * 1000000007;
const long long INFLL = 4LL * 1000000000 * 1000000000;

/***************/

int powmod (int a, int b, int mod) {
    int res = 1; a %= mod;
    for (; b; b >>= 1) {
        if (b & 1) {
            res = 1LL * res * a % mod;
        }
        a = 1LL * a * a % mod;
    }
    return res;
}

int gcd (int a, int b) {
    while (b > 0) {
        int t = a % b;
        a = b, b = t;
    }
    return a;
}

int lcm (int a, int b) {
    return (a / gcd (a, b)) * b;
}

int is_prime (int n) {
    if (n <= 1 || n > 3 && (n % 2 == 0 || n % 3 == 0))
        return 0;
    for (int i = 5, t = 2; i * i <= n; i += t, t = 6 - t)
        if (n % i == 0)
            return 0;
    return 1;
}

/******Don't forget to use long long when needed!!******/

int main() {
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    ios_base :: sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int n;
    cin >> n;
    int res = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            if (i + j < n && i < j && j < n - i - j) {
                res++;
            }
        }
    }
    cout << res << endl;
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED