1 #include <cstdio>
 2 #include <algorithm>
 3 using namespace std;
 4
 5 const int MN = 100005;
 6 const int MC = 100000;
 7
 8 int N, M;
 9 int A[MN], Mx[MN], Mn[MN];
10 int f[MN], Ans;
11 int p[MN];
12 inline bool cmp1(int i, int j) { return Mx[i] < Mx[j]; }
13 inline bool cmp2(int i, int j) { return A[i] < A[j]; }
14
15 int B[MN];
16 inline void Ins(int i, int x) { for (; i <= MC; i += i & -i) B[i] = max(B[i], x); }
17 inline void Clr(int i) { for (; i <= MC; i += i & -i) B[i] = 0; }
18 inline int Qur(int i) { int A = 0; for (; i; i -= i & -i) A = max(A, B[i]); return A;}
19
20 void CDQ(int lb, int rb) {
21     if (lb == rb) {
22         f[lb] = max(f[lb], 1);
23         return;
24     }
25     int mid = lb + rb >> 1;
26     CDQ(lb, mid);
27     for (int i = lb; i <= rb; ++i)
28         p[i] = i;
29     sort(p + lb, p + mid + 1, cmp1);
30     sort(p + mid + 1, p + rb + 1, cmp2);
31     int j = lb;
32     for (int i = mid + 1; i <= rb; ++i) {
33         while (j <= mid && Mx[p[j]] <= A[p[i]]) {
34             Ins(A[p[j]], f[p[j]]);
35             ++j;
36         }
37         f[p[i]] = max(f[p[i]], Qur(Mn[p[i]]) + 1);
38     }
39     for (int i = lb; i <= mid; ++i)
40         Clr(A[i]);
41     CDQ(mid + 1, rb);
42 }
43
44 int main() {
45     int x, y;
46     scanf("%d%d", &N, &M);
47     for (int i = 1; i <= N; ++i)
48         scanf("%d", &A[i]),
49         Mx[i] = Mn[i] = A[i];
50     for (int i = 1; i <= M; ++i)
51         scanf("%d%d", &x, &y),
52         Mx[x] = max(Mx[x], y),
53         Mn[x] = min(Mn[x], y);
54     CDQ(1, N);
55     for (int i = 1; i <= N; ++i)
56         Ans = max(Ans, f[i]);
57     printf("%d\n", Ans);
58     return 0;
59 }