Language: C++

#define bg begin()
#define ed end()
#define all(x) (x).bg,(x).ed
#define rep(i,n) for(ll i=0;i<(n);i++)
#define rep1(i,n) for(ll i=1;i<=(n);i++)
#define FOR(i,a,b) for(ll i=(a);i<(b);i++)

int main(){
	//input
	ll N,A; cin>>N>>A;
	vector<ll> X(N+1);
	rep1(i,N) cin>>X[i];

	ll dp[51][51][2501]; //dp[x][y][z]:x番目までy個選び和をzにする

	rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
	dp[1][0][0]=1;
	dp[1][1][X[1]]=1;

	FOR(i,2,51){
		rep(j,i+1){
			rep(k,2501){
				if(j!=0 && k>=X[i]) dp[i][j][k]+=dp[i-1][j-1][k-X[i]];
				dp[i][j][k]+=dp[i-1][j][k];
			}
		}
	}
	
	ll ans=0;
	rep1(i,50){
		if(i*A<=2500) ans+=dp[N][i][i*A];
	}

	cout<<ans;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:10:9: error: 'll' was not declared in this scope; did you mean 'all'?
   10 |         ll N,A; cin>>N>>A;
      |         ^~
      |         all
a.cc:10:17: error: 'cin' was not declared in this scope
   10 |         ll N,A; cin>>N>>A;
      |                 ^~~
a.cc:10:22: error: 'N' was not declared in this scope
   10 |         ll N,A; cin>>N>>A;
      |                      ^
a.cc:10:25: error: 'A' was not declared in this scope
   10 |         ll N,A; cin>>N>>A;
      |                         ^
a.cc:11:9: error: 'vector' was not declared in this scope
   11 |         vector<ll> X(N+1);
      |         ^~~~~~
a.cc:11:20: error: 'X' was not declared in this scope
   11 |         vector<ll> X(N+1);
      |                    ^
a.cc:12:14: error: expected ';' before 'i'
   12 |         rep1(i,N) cin>>X[i];
      |              ^
a.cc:5:26: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                          ^
a.cc:12:14: error: 'i' was not declared in this scope
   12 |         rep1(i,N) cin>>X[i];
      |              ^
a.cc:5:30: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                              ^
a.cc:14:11: error: expected ';' before 'dp'
   14 |         ll dp[51][51][2501]; //dp[x][y][z]:x番目までy個選び和をzにする
      |           ^~~
      |           ;
a.cc:16:14: error: expected ';' before 'i'
   16 |         rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
      |              ^
a.cc:5:26: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                          ^
a.cc:16:14: error: 'i' was not declared in this scope
   16 |         rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
      |              ^
a.cc:5:30: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                              ^
a.cc:16:24: error: expected ';' before 'j'
   16 |         rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
      |                        ^
a.cc:5:26: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                          ^
a.cc:16:24: error: 'j' was not declared in this scope
   16 |         rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
      |                        ^
a.cc:5:30: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                              ^
a.cc:16:33: error: expected ';' before 'k'
   16 |         rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
      |                                 ^
a.cc:4:25: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(ll i=0;i<(n);i++)
      |                         ^
a.cc:16:33: error: 'k' was not declared in this scope
   16 |         rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
      |                                 ^
a.cc:4:29: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(ll i=0;i<(n);i++)
      |                             ^
a.cc:16:41: error: 'dp' was not declared in this scope
   16 |         rep1(i,50)rep1(j,50)rep(k,2501) dp[i][j][k]=0;
      |                                         ^~
a.cc:17:9: error: 'dp' was not declared in this scope
   17 |         dp[1][0][0]=1;
      |         ^~
a.cc:20:13: error: expected ';' before 'i'
   20 |         FOR(i,2,51){
      |             ^
a.cc:6:27: note: in definition of macro 'FOR'
    6 | #define FOR(i,a,b) for(ll i=(a);i<(b);i++)
      |                           ^
a.cc:20:13: error: 'i' was not declared in this scope
   20 |         FOR(i,2,51){
      |             ^
a.cc:6:33: note: in definition of macro 'FOR'
    6 | #define FOR(i,a,b) for(ll i=(a);i<(b);i++)
      |                                 ^
a.cc:21:21: error: expected ';' before 'j'
   21 |                 rep(j,i+1){
      |                     ^
a.cc:4:25: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(ll i=0;i<(n);i++)
      |                         ^
a.cc:21:21: error: 'j' was not declared in this scope
   21 |                 rep(j,i+1){
      |                     ^
a.cc:4:29: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(ll i=0;i<(n);i++)
      |                             ^
a.cc:22:29: error: expected ';' before 'k'
   22 |                         rep(k,2501){
      |                             ^
a.cc:4:25: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(ll i=0;i<(n);i++)
      |                         ^
a.cc:22:29: error: 'k' was not declared in this scope
   22 |                         rep(k,2501){
      |                             ^
a.cc:4:29: note: in definition of macro 'rep'
    4 | #define rep(i,n) for(ll i=0;i<(n);i++)
      |                             ^
a.cc:29:11: error: expected ';' before 'ans'
   29 |         ll ans=0;
      |           ^~~~
      |           ;
a.cc:30:14: error: expected ';' before 'i'
   30 |         rep1(i,50){
      |              ^
a.cc:5:26: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                          ^
a.cc:30:14: error: 'i' was not declared in this scope
   30 |         rep1(i,50){
      |              ^
a.cc:5:30: note: in definition of macro 'rep1'
    5 | #define rep1(i,n) for(ll i=1;i<=(n);i++)
      |                              ^
a.cc:31:31: error: 'ans' was not declared in this scope
   31 |                 if(i*A<=2500) ans+=dp[N][i][i*A];
      |                               ^~~
a.cc:34:9: error: 'cout' was not declared in this scope
   34 |         cout<<ans;
      |         ^~~~
a.cc:34:15: error: 'ans' was not declared in this scope
   34 |         cout<<ans;
      |               ^~~