#include<iostream>
#include<cstdio>
#include<algorithm>
#include<functional>
#include<queue>
#include<vector>
#include<set>
#include<cstring>
#include<string>
#include<stack>

const int maxn = 100000 + 5;
using namespace std;

#define rep(i, j, k) for(int i = j; i <= k; i++)
#define drep(i, j, k) for(int i = j; i >= k; i--)
#define INF 0x3fffffff
#define LL long long

inline int read()
{
    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 - '0'; ch = getchar();}
    return x * f;
}

struct point {
    int L, R;
}a[maxn];

multiset<int>s;
int m, n, Ar, Sa, cnt, ans, tot, b1, b2;
int vis[maxn];
/*
bool cmp(const point i, const point j) {
    if(i.L != j.L) return i.L < j.L;
    else return i.R < j.R;
}*/
bool cmp(const point i, const point j) {
    return i.R - i.L < j.R - j.L;
}

void init()
{
    n = read(), m = read();
    rep(i, 1, n) {Ar = read(); b1 = min(b1, Ar); s.insert(Ar);}
    rep(i, 1, m) a[i].L = read(), a[i].R = read();
}

void print()
{
    rep(i, 1, m) { cout<<a[i].L<<" "<<a[i].R<<endl; }
}

int main()
{
    freopen("bg.in", "r", stdin);
    freopen("bg.out", "w", stdout);
    init();
    sort(a + 1, a + 1 + m, cmp);
    set<int>::iterator it;
    rep(i, 1, m) {
        rep(j, a[i].L, a[i].R)
            if(s.count(j)) {
                ans++, s.erase(j);
                break;
            }
    }
    cout<<ans<<endl;
}