1 #include<cstdio>
2 #define MAXN 50010
3 #define INF 987654321
4 int a[MAXN<<2],b[MAXN<<2];
5 inline int MAX(int x,int y)
6 {
7 return x>y?x:y;
8 }
9 inline int MIN(int x,int y)
10 {
11 return x>y?y:x;
12 }
13 inline void PushUp(int rt)
14 {
15 a[rt]=MAX(a[rt<<1],a[rt<<1|1]);
16 b[rt]=MIN(b[rt<<1],b[rt<<1|1]);
17 }
18 void Build(int L,int R,int rt)
19 {
20 if(L==R)
21 {
22 scanf("%d",&a[rt]);
23 b[rt]=a[rt];
24 }
25 else
26 {
27 int mid=(L+R)>>1;
28 Build(L,mid,rt<<1);
29 Build(mid+1,R,rt<<1|1);
30 PushUp(rt);
31 }
32 }
33 int Big(int x,int y,int L,int R,int rt)
34 {
35 if(x<=L&&R<=y)
36 return a[rt];
37 int mid,ans;
38 mid=(L+R)>>1;
39 ans=-INF;
40 if(mid>=x)
41 ans=MAX(ans,Big(x,y,L,mid,rt<<1));
42 if(y>mid)
43 ans=MAX(ans,Big(x,y,mid+1,R,rt<<1|1));
44 return ans;
45 }
46 int Small(int x,int y,int L,int R,int rt)
47 {
48 if(x<=L&&R<=y)
49 return b[rt];
50 int mid,ans;
51 mid=(L+R)>>1;
52 ans=INF;
53 if(mid>=x)
54 ans=MIN(ans,Small(x,y,L,mid,rt<<1));
55 if(y>mid)
56 ans=MIN(ans,Small(x,y,mid+1,R,rt<<1|1));
57 return ans;
58 }
59 int main()
60 {
61 int n,q,x,y;
62 while(~scanf("%d%d",&n,&q))
63 {
64 Build(1,n,1);
65 while(q--)
66 {
67 scanf("%d%d",&x,&y);
68 printf("%d\n",Big(x,y,1,n,1)-Small(x,y,1,n,1));
69 }
70 }
71 return 0;
72 }
