#include <iostream>
#include <cstring>
#include <algorithm>
#define x first
#define y second

using namespace std;

typedef pair<int, int> PII;

const int N = 40010;

PII ps[N];
int n, X, Y, Z, ans;

int main()
{
    scanf("%d%d%d%d", &n, &X, &Y, &Z);

    for (int i = 1; i < n * 2; i += 2)
    {
        int a, b;
        scanf("%d%d", &a, &b);
        ps[i] = {a, Y - X};
        ps[i + 1] = {b + 1, Z - Y};
    }

    sort(ps + 1, ps + n * 2 + 1);

    int res = n * X;
    for (int i = 1; i <= n * 2; i ++)
    {
        res += ps[i].y;
        ans = max(ans, res);
    }

    printf("%d", ans);

    return 0;
}