_altf4_and_the_beetles.cpp

#include <iostream>
#include <algorithm>

using namespace std;

template <typename T> inline void inp (T &n) {
	n = 0;
	int ch = getchar_unlocked (), sign = 1;
	while (ch < '0' || ch > '9') {
		if (ch == '-') sign = -1; 
		ch = getchar_unlocked ();
	}
	while (ch >= '0' && ch <= '9')
		n = (n << 3) + (n << 1) + ch - '0', ch = getchar_unlocked ();
	n *= sign;
}

template <typename T> inline void puti (T n, char lc) {
	if (0 == n) {
        putchar_unlocked ('0');
        if (lc) putchar_unlocked (lc);
        return;
	}
    //bool sign = false;
	//if (n < 0) sign = true, n = -n;
    char s[20]; int rdi =-1;
	while (n) {
		s [++rdi] = '0' + n % 10;
		n /= 10;
	}
    //if (sign) putchar_unlocked ('-');
	while (rdi >= 0) putchar_unlocked (s [rdi--]);
	if (lc) putchar_unlocked (lc);
}

bool cmp (pair <int, int> a, pair <int, int> b) {
    if (a.first == b.first) return a.second > b.second;
    else return a.first < b.first;
}

int main () {
    ios_base::sync_with_stdio (false); cin.tie (NULL); cout.tie (NULL);
    int t, n, n2, i, a, b, c, ba, cb, p, q;
    long long count, ans;
    inp (t);
    while (t--) {
        inp (n); inp (a); inp (b); inp (c);
        ba = b - a; cb = c - b; n2 = 2 * n;
        pair <int, int> v [n2];
        for (i = 0; i < n2; i+= 2) inp (p), inp (q), v [i] = {p, ba}, v [i + 1] = {q, cb};
        ans = 0; count = (long long) n * a;
        sort (v, v + n2, cmp);
        for (auto p : v) {count += p.second; if (count > ans) ans = count;}
        puti (ans, '\n');
    }
    return 0;
}