#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int NumTriplesWithSumX(
        vector<int>& a,
        vector<int>& b,
        vector<int>& c,
        int x
)
{
    /*
    int l1 = v1.size();
    int l2 = v2.size();
    int l3 = v3.size();

    vector<int> *p_short, *p_long1, *p_long2;

    if (l1 <= l2 && l1 <= l3) {
        p_short = &v1;
        p_long1 = &v2;
        p_long2 = &v3;
    } else if (l2 <= l1 && l2 <= l3) {
        p_short = &v2;
        p_long1 = &v1;
        p_long2 = &v3;
    } else { // v3 is the shortest
        p_short = &v3;
        p_long1 = &v1;
        p_long2 = &v2;
    }

    vector<int>& a = *p_long1;
    vector<int>& b = *p_long2;
    vector<int>& c = *p_short;
*/
    sort(a.begin(), a.end());
    sort(b.begin(), b.end());
    reverse(b.begin(), b.end());

    int ans = 0;
    const int n = a.size();
    const int m = b.size();

    for (auto num : c) {
        int required_value = x - num;
        int i = 0;
        int j = 0;
        while (i < n && j < m) {
            if (a[i] + b[j] < required_value){
                ++i;
            } else if (a[i] + b[j] > required_value) {
                ++j;
            } else {
                int flag_a = i++;
                while (i < n && a[i] == a[i - 1]) {
                    i++;
                }
                int flag_b = j++;
                while (j < m && b[j] == b[j - 1]) {
                    j++;
                }
                ans += (i - flag_a) * (j - flag_b);
            }
        }
    }

    return ans;
}
int main() {
    {
        vector<int> a = {1, 1, 1, 2, 2, 3, 4, 4};
        vector<int> b = {8,7,5,4,4,4,3,3,1,1,1,0};
        vector<int> c = {0};
        cout << NumTriplesWithSumX(a, b, c, 5) << endl;
    }
    {
        vector<int> b = {1, 1, 1, 2, 2, 3, 4, 4};
        vector<int> c = {8,7,5,4,4,4,3,3,1,1,1,0};
        vector<int> a = {0};
        cout << NumTriplesWithSumX(a, b, c, 5) << endl;
    }
    {
        vector<int> a = {1, 1, 1, 1, 1, 1};
        vector<int> b = {2, 2, 2, 2};
        vector<int> c = {3, 3};
        cout << NumTriplesWithSumX(a, b, c, 6) << endl;
    }
    {
        vector<int> a = {};
        vector<int> b = {1, 1, 1, 1};
        vector<int> c = {0};
        cout << NumTriplesWithSumX(a, b, c, 1) << endl;
    }

    return 0;
}