#include<bits/stdc++.h> using namespace std; #define foru(i,a,b) for(int i=(a); i<=(b); ++i) #define ford(i,a,b) for(int i=(a); i>=(b); --i) #define rep(i,a) for(int i=0; i<(a); ++i) #define sz(a) (int)(a).size() #define all(a) (a).begin(),(a).end() #define bit(s,i) (((s)>>(i))&1) #define ii pair<int,int> #define vi vector<int> #define vii vector<ii> #define fi first #define se second #define ll long long #define eb emplace_back #define pb push_back #define __builtin_popcount __builtin_popcountll #define _ << " " << template <class X, class Y> bool maxi(X &x, Y y){return x<y?x=y,true:false;} template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;} const int N=505050; const int mod=1e9+7; int n,m,A[N],B[N],dp[N][26]; int unsum[26],msum[26],psum[26]; priority_queue<int,vector<int>,greater<int>> una,ma,pa; vector<ii> seg[N]; inline int add(int a, int b){ a+=b; if(a>=mod) a-=mod; return a; } inline int sub(int a, int b){ a-=b; if(a<0) a+=mod; return a; } void solve(){ cin>>n>>m; foru(i,1,m){ cin>>A[i]>>B[i]; if(A[i]<B[i]){ seg[A[i]].eb(B[i],1); } else{ seg[B[i]].eb(A[i],-1); } } ford(i,n,1){ for(auto [r,type]:seg[i]){ if(type==1){ int tmp=0; while(sz(una) && una.top()<=r){ int id=una.top(); una.pop(); pa.push(id); int tot=0; rep(c,26) tot=add(tot,dp[id][c]); rep(c,26) unsum[c]=sub(unsum[c], sub(tot,dp[id][c])); tmp=0; rep(c,26){ psum[c]=add(psum[c],tmp); tmp=add(tmp,dp[id][c]); } } while(sz(ma) && ma.top()<=r){ int id=ma.top(); ma.pop(); tmp=0; ford(c,25,0){ msum[c]=sub(msum[c],tmp); tmp=add(tmp,dp[id][c]); } } } else{ int tmp=0; while(sz(una) && una.top()<=r){ int id=una.top(); una.pop(); ma.push(id); int tot=0; rep(c,26) tot=add(tot,dp[id][c]); rep(c,26) unsum[c]=sub(unsum[c], sub(tot,dp[id][c])); tmp=0; ford(c,25,0){ msum[c]=add(msum[c],tmp); tmp=add(tmp,dp[id][c]); } } while(sz(pa) && pa.top()<=r){ int id=pa.top(); pa.pop(); tmp=0; rep(c,26){ psum[c]=sub(psum[c],tmp); tmp=add(tmp,dp[id][c]); } } } } rep(c,26){ dp[i][c]=1; dp[i][c]=add(dp[i][c],add(unsum[c],add(msum[c],psum[c]))); } int tot=0; rep(c,26) tot=add(tot,dp[i][c]); rep(c,26) unsum[c]=add(unsum[c],sub(tot,dp[i][c])); una.push(i); } int tot=0; rep(c,26) tot=add(tot,dp[1][c]); cout<<tot<<'\n'; } int32_t main(){ #define task "test" if(fopen(task".inp", "r")){ freopen(task".inp", "r", stdin); freopen(task".out", "w", stdout); } cin.tie(0)->sync_with_stdio(0); int tc=1; //cin>>tc; foru(i,1,tc){ solve(); } }

misspelling.cpp: In function 'int32_t main()':
misspelling.cpp:126:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
misspelling.cpp:127:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  127 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~