#include <iostream>
#include <algorithm>
using namespace std;

struct stu
{
	int v, x;
}a[100010], b[100010], c[100010];
long long ans, s[100010];

bool cmp(stu x, stu y)
{
	return x.v < y.v;
}

void f(int l, int r)
{
	if (l >= r)  return;
	int m = (l + r) / 2, pos = l;
	f(1, m);
	f(m + 1, r);
	s[l - 1] = 0;
	for (int i = l; i <= r; i++)
	{
		if (i <= m)  s[i] = s[i - 1] + a[i].x;
		else
		{
			while (pos <= m && a[pos].x < a[i].x)  pos++;
			ans += 1ll * (1ll * (pos + pos - l - m - 1) * a[i].x + s[m] - s[pos - 1] * 2) * a[i].v;
		}
	}
	for (int i = l; i <= r; i++)
	{
		if (i <= m)  b[i] = a[i];
		else  c[i] = a[i];
	}
	b[m + 1].x = c[r + 1].x = 1e9;
	for (int i = l, j = l, k = m + 1; i <= r; i++)
	{
		a[i] = b[j].x < c[k].x ? b[j++] : c[k++];
	}
}

int main()
{
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i].v >> a[i].x;
	}
	sort(a + 1, a + n + 1, cmp);
	f(1, n);
	cout << ans;
	return 0;
}