code:

#include<bits/stdc++.h>
using namespace std;
int f[600000][21],g[600000][21];
//f[i][j]=max(a[i-->(1<<j)])
int lg[600000],n,m,l,r;
void LOG(){
    lg[1]=0,lg[2]=1;
    for(register int i=3;i<=n;++i){
        lg[i]=lg[i>>1]+1;
    }
}
inline int read()
{
	register int x=0,f=1;char ch=getchar();
	while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}
	while (ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();}
	return x*f;
}
int main(){
    n=read();m=read();
    LOG();
    for(register int i=1;i<=n;i++)g[i][0]=f[i][0]=read();
    for(register int j=1;j<=26;j++){
        for(register int i=1;i+(1<<j)-1<=n;i++){
            f[i][j]=max(f[i][j-1],f[i+(1<<(j-1))][j-1]);
            g[i][j]=min(f[i][j-1],f[i+(1<<(j-1))][j-1]);
        }
    }
    for(register int i=1;i<=m;i++){
        l=read();r=read();
        int LG=lg[r-l+1];
        int ans=max(f[l][LG],f[r-(1<<LG)+1][LG]);
        int ansp=min(g[l][LG],g[r-(1<<LG)+1][LG]);
        printf("%d\n",ans-ansp);
    }
    return 0;
}