Can you please help me see my mistake, in Subarray Sums || It gives WA for 2 cases.

int main(){
  FastIO;
  int n;
  ll x;
  cin>>n>>x;
  ll a[n];
  ll prefix[n];
  for(int i=0;i<n;i++){
    cin>>a[i];
    prefix[i] = a[i];
    if(i>0) prefix[i]+=prefix[i-1];
  }
  map<ll,ll>cache;
  int cnt =0;
  for(int i =0;i<n;i++){
    cache[prefix[i]]+=1;
    if(prefix[i]==x and cache[0]==0) cnt+=1;
    else cnt+=cache[prefix[i]-x];
  }
  cout<<cnt;
  return 0;
}