This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
// Om Namah Shivaya
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)
template<typename T>
void amin(T &a, T b) {
a = min(a, b);
}
template<typename T>
void amax(T &a, T b) {
a = max(a, b);
}
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
/*
*/
const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
void solve(int test_case)
{
ll n, m; cin >> n >> m;
vector<array<ll, 3>> a(m);
rep(i, m) {
ll l, r; cin >> l >> r;
ll t = 0;
if (l > r) {
swap(l, r);
t = 1;
}
a[i] = {t, l, r - 1};
}
ll dp[n + 5][n + 5][26];
memset(dp, 0, sizeof dp);
rep(ch, 26) {
dp[1][1][ch] = 1;
}
rep1(i, n - 1) {
rep1(p, i) {
ll les = 0, mor = 0;
rep(j, m) {
auto [t, l, r] = a[j];
if (l >= p and l <= i) {
if (r >= i) {
if (t == 0) les++;
else mor++;
}
}
}
rep(ch1, 26) {
if (!dp[i][p][ch1]) conts;
rep(ch2, 26) {
if (ch2 < ch1 and !mor) {
dp[i + 1][i + 1][ch2] = (dp[i + 1][i + 1][ch2] + dp[i][p][ch1]) % MOD;
}
if (ch2 == ch1) {
dp[i + 1][p][ch2] = (dp[i + 1][p][ch2] + dp[i][p][ch1]) % MOD;
}
if (ch2 > ch1 and !les) {
dp[i + 1][i + 1][ch2] = (dp[i + 1][i + 1][ch2] + dp[i][p][ch1]) % MOD;
}
}
}
}
}
ll ans = 0;
rep1(p, n) {
rep(ch, 26) {
ans = (ans + dp[n][p][ch]) % MOD;
}
}
cout << ans << endl;
}
int main()
{
fastio;
int t = 1;
// cin >> t;
rep1(i, t) {
solve(i);
}
return 0;
}
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