/in/foo.cc: In function 'int main()':
/in/foo.cc:7:8: error: 'i' was not declared in this scope
  int a[i][j];
        ^
/in/foo.cc:7:11: error: 'j' was not declared in this scope
  int a[i][j];
           ^
/in/foo.cc:9:18: error: expected ';' before ')' token
  for (i=0;i<n,i++)
                  ^
/in/foo.cc:11:19: error: expected ';' before ')' token
   for (j=0;j<n,j++)
                   ^
/in/foo.cc:13:9: error: 'a' was not declared in this scope
    cin>>a[i][j];
         ^