#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <queue>
#include <algorithm>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <memory.h>
#include <ctime>

using namespace std;

#define ABS(a) ((a>0)?a:-(a))
#define MIN(a,b) ((a<b)?(a):(b))
#define MAX(a,b) ((a<b)?(b):(a))
#define FOR(i,a,n) for (int i=(a);i<(n);++i)
#define FI(i,n) for (int i=0; i<(n); ++i)
#define pnt pair <int, int>
#define mp make_pair
#define PI 3.14159265358979
#define MEMS(a,b) memset(a,b,sizeof(a))
#define LL long long
#define U unsigned

int a[200100];
int val[200100];
int b[200100];
int main()
{
    int n,q;
    scanf("%d%d",&n,&q);
    FOR(i,0,n)
        scanf("%d",&a[i]);
    sort(a,a+n);
    FOR(i,0,q)
    {
        int l,r;
        scanf("%d%d",&l,&r);
        l--;
        r--;
        val[l]++;
        if (r<n-1)
            val[r+1]--;
    }
    int v=0;
    FOR(i,0,n)
    {
        v+=val[i];
        b[i]=v;
    }
    sort(b,b+n);
    LL res=0;
    FOR(i,0,n)
        res+=(b[i]*1ll*a[i]);
    cout<<res<<endl;
    return 0;
}