// Problem: A. t3
// Contest: undefined - NOIP2024训练赛 09
// URL: http://www.noi.ac/contest/1161/problem/574
// Memory Limit: 256 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define PII pair<int, int>

using namespace std;

const int N = 2e5 + 10, M = 1e6 + 10, mod = 1e9 + 7, INF = 0x3f3f3f3f;

int n, m, q, ans, a, b, c;
int dp[N], val[3];
PII s[N];

vector<int> e[N];

priority_queue<int> pq[3];

signed main()
{
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n >> val[0] >> val[1] >> c; 
	for(int i = 1; i <= n; i ++) cin >> s[i].fi >> s[i].se;
	for(int i = 1; i <= n; i ++)
	{
		if(s[i].fi == s[i].se) continue;
		int now = s[i].se < s[i].fi;
		for(int j = 1; j <= abs(s[i].fi - s[i].se); j ++)
		{
			if(pq[now].empty() || i * c - pq[now].top() > val[now]) ans += val[now], pq[now ^ 1].push(i * c + val[now]);
			else ans += i * c - pq[now].top(), pq[now ^ 1].push(i * c * 2 - pq[now].top()), pq[now].pop();
		}
	}
	cout << ans << '\n';
	return 0;
}