#include <iostream>
using namespace std;

int main ()
{
	int n, m, pk=0, ok, c, pd=0, od, kg, tmp;
	cin >> n >> m;
	int t[n];
	for (int i = 0; i < n; ++i)
		cin >> t[i];
	while(m--)
	{
		kg = 0;
	
		cin >> ok;
		c = ok - pk;
		pk = ok;
		
		cin >> od;
		for (int i = 0; i < n; ++i)
		{
			tmp = pd+t[i]*c - od;
			if (tmp > 0)
				kg += tmp;
		}
		pd = od;
		cout << kg << '\n';
	}
	
	return 0;
}