foo.cc: In function 'int main()':
foo.cc:8:7: error: 'n' was not declared in this scope
    8 |  cin>>n;
      |       ^
foo.cc:9:6: error: 'i' was not declared in this scope
    9 |  for(i=1;i<=n;i++)
      |      ^
foo.cc:11:7: error: 'j' was not declared in this scope
   11 |   for(j=1,j<=2*i-1;j++)
      |       ^
foo.cc:11:23: error: expected ';' before ')' token
   11 |   for(j=1,j<=2*i-1;j++)
      |                       ^
      |                       ;

[Hydro](https://hydro.ac)提供评测服务