foo.cc: In function ‘int main()’:
foo.cc:6:9: error: ‘for9int’ was not declared in this scope
    6 |         for9int i=1;i<=n;i++;
      |         ^~~~~~~
foo.cc:6:21: error: ‘i’ was not declared in this scope
    6 |         for9int i=1;i<=n;i++;
      |                     ^
foo.cc:6:24: error: ‘n’ was not declared in this scope
    6 |         for9int i=1;i<=n;i++;
      |                        ^