Language: C++

l#include<bits/stdc++.h>

typedef long long ll;

const ll N = 3010;
const ll moder = 1e9 + 7;

ll dp[N][N << 1];

ll &getdp(ll i, ll j){
    return dp[i][j + N];
}

void add(ll &a, ll b){
    a += b;
    a -= a >= moder ? moder : 0;
    a += a < 0 ? moder : 0;
}

void addmult(ll &a, ll b, ll c){
    a = (a + 1ll * b * c) % moder;
    a += a < 0 ? moder : 0;
}

int main(){
    ll n, m;
    scanf("%lld%lld", &n, &m);
    getdp(0, 0) = 1;
    for (ll i = 0; i < m - 1; ++ i){
        for (ll j = 1 - n; j <= n - 1; ++ j){
            addmult(getdp(i + 1, j), 2, getdp(i, j));
            add(getdp(i + 1, j - 1), getdp(i, j));
            add(getdp(i + 1, j + 1), getdp(i, j));
        }
    }
    ll ans = 0;
    for (ll i = 1 - n; i <= n - 1; ++ i){
        addmult(ans, 4, getdp(m - 1, i));
    }
    printf("%lld\n", ans);
    return 0;
}

Compiler output:
a.cc:1:2: error: stray '#' in program
    1 | l#include<bits/stdc++.h>
      |  ^
a.cc:1:1: error: 'l' does not name a type
    1 | l#include<bits/stdc++.h>
      | ^
a.cc:5:7: error: 'll' does not name a type
    5 | const ll N = 3010;
      |       ^~
a.cc:6:7: error: 'll' does not name a type
    6 | const ll moder = 1e9 + 7;
      |       ^~
a.cc:8:1: error: 'll' does not name a type
    8 | ll dp[N][N << 1];
      | ^~
a.cc:10:1: error: 'll' does not name a type
   10 | ll &getdp(ll i, ll j){
      | ^~
a.cc:14:6: error: variable or field 'add' declared void
   14 | void add(ll &a, ll b){
      |      ^~~
a.cc:14:10: error: 'll' was not declared in this scope
   14 | void add(ll &a, ll b){
      |          ^~
a.cc:14:14: error: 'a' was not declared in this scope
   14 | void add(ll &a, ll b){
      |              ^
a.cc:14:17: error: 'll' was not declared in this scope
   14 | void add(ll &a, ll b){
      |                 ^~
a.cc:20:6: error: variable or field 'addmult' declared void
   20 | void addmult(ll &a, ll b, ll c){
      |      ^~~~~~~
a.cc:20:14: error: 'll' was not declared in this scope
   20 | void addmult(ll &a, ll b, ll c){
      |              ^~
a.cc:20:18: error: 'a' was not declared in this scope
   20 | void addmult(ll &a, ll b, ll c){
      |                  ^
a.cc:20:21: error: 'll' was not declared in this scope
   20 | void addmult(ll &a, ll b, ll c){
      |                     ^~
a.cc:20:27: error: 'll' was not declared in this scope
   20 | void addmult(ll &a, ll b, ll c){
      |                           ^~
a.cc: In function 'int main()':
a.cc:26:5: error: 'll' was not declared in this scope
   26 |     ll n, m;
      |     ^~
a.cc:27:24: error: 'n' was not declared in this scope
   27 |     scanf("%lld%lld", &n, &m);
      |                        ^
a.cc:27:28: error: 'm' was not declared in this scope
   27 |     scanf("%lld%lld", &n, &m);
      |                            ^
a.cc:27:5: error: 'scanf' was not declared in this scope
   27 |     scanf("%lld%lld", &n, &m);
      |     ^~~~~
a.cc:28:5: error: 'getdp' was not declared in this scope
   28 |     getdp(0, 0) = 1;
      |     ^~~~~
a.cc:29:12: error: expected ';' before 'i'
   29 |     for (ll i = 0; i < m - 1; ++ i){
      |            ^~
      |            ;
a.cc:29:20: error: 'i' was not declared in this scope
   29 |     for (ll i = 0; i < m - 1; ++ i){
      |                    ^
a.cc:30:16: error: expected ';' before 'j'
   30 |         for (ll j = 1 - n; j <= n - 1; ++ j){
      |                ^~
      |                ;
a.cc:30:28: error: 'j' was not declared in this scope
   30 |         for (ll j = 1 - n; j <= n - 1; ++ j){
      |                            ^
a.cc:31:13: error: 'addmult' was not declared in this scope
   31 |             addmult(getdp(i + 1, j), 2, getdp(i, j));
      |             ^~~~~~~
a.cc:32:13: error: 'add' was not declared in this scope
   32 |             add(getdp(i + 1, j - 1), getdp(i, j));
      |             ^~~
a.cc:36:7: error: expected ';' before 'ans'
   36 |     ll ans = 0;
      |       ^~~~
      |       ;
a.cc:37:12: error: expected ';' before 'i'
   37 |     for (ll i = 1 - n; i <= n - 1; ++ i){
      |            ^~
      |            ;
a.cc:37:24: error: 'i' was not declared in this scope
   37 |     for (ll i = 1 - n; i <= n - 1; ++ i){
      |                        ^
a.cc:38:17: error: 'ans' was not declared in this scope
   38 |         addmult(ans, 4, getdp(m - 1, i));
      |                 ^~~
a.cc:38:9: error: 'addmult' was not declared in this scope
   38 |         addmult(ans, 4, getdp(m - 1, i));
      |         ^~~~~~~
a.cc:40:22: error: 'ans' was not declared in this scope
   40 |     printf("%lld\n", ans);
      |                      ^~~
a.cc:40:5: error: 'printf' was not declared in this scope
   40 |     printf("%lld\n", ans);
      |     ^~~~~~
a.cc:1:1: note: 'printf' is defined in header '<cstdio>'; this is probably fixable by adding '#include <cstdio>'
  +++ |+#include <cstdio>
    1 | l#include<bits/stdc++.h>