#include<bits/stdc++.h>
using namespace std;
int n, q;
int a[50001];
int f1[50001][20], f2[50001][20];
inline void work1()
{
	for(int i = 1; i <= n; i++)
		f1[i][0] = a[i];
	for(int j = 1; (1 << j) <= n; j++)
		for(int i = 1; i + (1 << j) - 1 <= n; i++)
			f1[i][j] = max(f1[i][j - 1], f1[i << (j - 1)][j - 1]);
}
inline int RMQ1(int l, int r)
{
	int cnt = 0;
	while((1 << (cnt + 1)) <= r - l + 1) cnt++;
	return max(f1[l][cnt], f1[r - (1 << cnt) + 1][cnt]);
}
inline void work2()
{
	for(int i = 1; i <= n; i++)
		f2[i][0] = a[i];
	for(int j = 1; (1 << j) <= n; j++)
		for(int i = 1; i + (1 << j) - 1 <= n; i++)
			f2[i][j] = min(f2[i][j - 1], f2[i << (j - 1)][j - 1]);
}
inline int RMQ2(int l, int r)
{
	int cnt = 0;
	while((1 << (cnt + 1)) <= r - l + 1) cnt++;
	return min(f2[l][cnt], f2[r - (1 << cnt) + 1][cnt]);
}
int main()
{
	cin >> n >> q;
	for(int i = 1; i <= n; i++)
		cin >> a[i];
	work1(); work2();
	while(q--)
	{
		int x, y;
		cin >> x >> y;
		cout << RMQ1(x, y) - RMQ2(x, y) << endl;
	}
	return 0;
}

萌新刚学RMQ，还不熟，求大佬指导。