#include <algorithm>
#include <cstdint>
#include <iostream>
#define EVAL(x) cout << #x " = " << x << "\n"

namespace {
using std::cin;
using std::cout;
using std::int64_t;

const int kP = 998244353;

namespace mod {
inline int Mod(int x) { return x >= kP ? x - kP : x; }
inline void Add(int &x, int y) { x = Mod(x + y); }
}  // namespace mod

const int kMaxN = 5.0e5 + 5;
int n, m;
int lt_bound[kMaxN], gt_bound[kMaxN];
int f[kMaxN][26];
}  // namespace

int main() {
  cin.tie(nullptr);
  std::ios::sync_with_stdio(false);
  cin >> n >> m;

  while (m--) {
    int a, b;
    cin >> a >> b;

    if (a < b) {
      gt_bound[a] = std::max(gt_bound[a], b - 1);
    } else {
      lt_bound[b] = std::max(lt_bound[b], a - 1);
    }
  }

  std::fill_n(f[0], 26, 1);

  for (int i = 0; i < n - 1; ++i) {
    for (int c = 0; c < 26; ++c) {
      // EVAL(i), EVAL(c), EVAL(f[i][c]);

      for (int next_c = 0; next_c < 26; ++next_c) {
        if (c == next_c) continue;

        if (c < next_c) {
          int max = 0;

          for (int j = i + 1; j <= n - 1; ++j) {
            max = std::max(max, gt_bound[j]);
            if (j > max) mod::Add(f[j][next_c], f[i][c]);
          }
        } else {
          int max = 0;

          for (int j = i + 1; j <= n - 1; ++j) {
            max = std::max(max, lt_bound[j]);
            if (j > max) mod::Add(f[j][next_c], f[i][c]);
          }
        }
      }
    }
  }

  int ans = 0;

  for (int i = 0; i <= n - 1; ++i) {
    for (int c = 0; c < 26; ++c) mod::Add(ans, f[i][c]);
  }

  cout << ans << "\n";
  return 0;
}