This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include<bits/stdc++.h>
using namespace std;
// #define int long long
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define isz(x) ((int)x.size())
#define sumof(x) accumulate(all(x), 0ll)
const int N=5e5+10, mod=1e9+7;
int n, m;
int f[N][26], ff[N][26];
vector<pair<int, int>> g[N];
int pf[2][26];
int add(int x, int y){
   return x+y>=mod?x+y-mod:x+y;
}
int sub(int x, int y){
   return x<y?x-y+mod:x-y;
}
void solve(){
   cin >> n >> m;
   for (int i=1; i<=m; ++i){
      int u, v; cin >> u >> v;
      if (u<v){
         g[u].emplace_back(v, 0);
      }else{
         g[v].emplace_back(u, 1);
      }
   }
   vector<set<int>> pos(2);
   for (int i=1; i<=n; ++i) pos[0].insert(i);
   pos[1]=pos[0];
   for (int i=0; i<26; ++i) f[n][i]=1, ff[n][i]=i+1;
   for (int i=0; i<26; ++i) pf[0][i]=pf[1][i]=i+1;
   for (int i=n-1; i>=1; --i){
      for (auto &j:g[i]){
         int l=i+1, r=j.first, k=j.second;
         for (auto it=pos[k^1].lower_bound(l); it!=pos[k^1].end() && (*it)<=r; it=pos[k^1].erase(it)){
            for (int t=0; t<26; ++t) pf[k^1][t]=sub(pf[k^1][t], ff[*it][t]);
         }
      }
      for (int j=0; j<26; ++j){
         f[i][j]=1;
         if (j) f[i][j]=add(f[i][j], pf[0][j-1]);
         f[i][j]=add(f[i][j], sub(pf[1][25], pf[1][j]));
      }
      for (int j=0; j<26; ++j){
         ff[i][j]=f[i][j];
         if (j) ff[i][j]=add(ff[i][j], ff[i][j-1]);
         pf[0][j]=add(pf[0][j], ff[i][j]);
         pf[1][j]=add(pf[1][j], ff[i][j]);
      }
   }
   int ans=0;
   for (int j=0; j<26; ++j) ans=add(ans, f[1][j]);
   cout << ans;
}
int32_t main(){
   ios_base::sync_with_stdio(false);
   cin.tie(nullptr);
   int ntests=1;
   // cin >> ntests;
   for (int i=1; i<=ntests; ++i) solve();
   return 0;
}
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