#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=3030; const int mod=1e9+7; int h,w,dp[N][N]; void solve(){ cin>>h>>w; foru(i,0,max(h,w)) dp[i][0]=dp[0][i]=1; foru(i,1,h) foru(j,1,w){ dp[i][j]=dp[i-1][j]; if(j>=2) dp[i][j]=(dp[i][j] + 1LL * j*(j-1)/2 * dp[i-1][j-2] % mod) % mod; if(i>=2) dp[i][j]=(dp[i][j] + 1LL * j*(i-1) * dp[i-2][j-1] % mod) % mod; dp[i][j]=(dp[i][j]+ 4LL*j*dp[i-1][j-1] % mod) % mod; } cout<<(dp[h][w]+mod-1)%mod<<'\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(); } }

tents.cpp: In function 'int32_t main()':
tents.cpp:45:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:46:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~