// Question 2
import java.io.*;
import java.util.*;

public class a {

    private static boolean[][] visited;
    private static ArrayList<HashSet<Integer>> bootsAccessible;

    private static class Boot {
        private int s;
        private int d;

        public Boot(int s, int d) {
            this.s = s;
            this.d = d;
        }
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("snowboots.in"));
        PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("snowboots.out")));
        StringTokenizer st = new StringTokenizer(br.readLine());

        int n = Integer.parseInt(st.nextToken());
        int b = Integer.parseInt(st.nextToken());

        int[] path = new int[n];
        st = new StringTokenizer(br.readLine());

        for(int i = 0; i < n; i++) {
            path[i] = Integer.parseInt(st.nextToken());
        }

        Boot[] boots = new Boot[b];

        for(int i = 0; i < b; i++) {
            st = new StringTokenizer(br.readLine());
            int s = Integer.parseInt(st.nextToken());
            int d = Integer.parseInt(st.nextToken());
            boots[i] = new Boot(s, d);
        }

        br.close();

        bootsAccessible = new ArrayList<HashSet<Integer>>();

        for(int i = 0; i < n; i++) {
            bootsAccessible.add(new HashSet<Integer>());
            for(int j = 0; j < b; j++) {
                if(boots[j].s >= path[i]) {
                    bootsAccessible.get(i).add(j);
                }
            }
        }

        visited = new boolean[n][b];

        floodfill(0, 0, boots, n);

        int minBoots = 0;

        for(int i = 0; i < b; i++) {
            if(visited[n-1][i]) {
                minBoots = i;
                break;
            }
        }

        pw.print(minBoots);
        pw.close();
    }

    public static void floodfill(int tileInd, int bootInd, Boot[] boots, int n) {
        if(tileInd >= n || bootInd >= boots.length || visited[tileInd][bootInd]) {
            return;
        }
        visited[tileInd][bootInd] = true;
        for(int i = 1; i <= boots[bootInd].d; i++) {
            if(tileInd + i < n && bootsAccessible.get(tileInd + i).contains(bootInd)) {
                floodfill(tileInd + i, bootInd, boots, n);
            }
        }
        for(int i = bootInd + 1; i < boots.length; ++i) {
            if(bootsAccessible.get(tileInd).contains(i)) {
                floodfill(tileInd, i, boots, n);
            }
        }
    }

}