Compilation failed: 7 error(s), 0 warnings

/w/foo.cs(2,0): error CS1024: Wrong preprocessor directive
/w/foo.cs(3,0): error CS1024: Wrong preprocessor directive
/w/foo.cs(3,6): error CS1525: Unexpected symbol `namespace', expecting `identifier' or `static'
/w/foo.cs(3,19): error CS1525: Unexpected symbol `;', expecting `identifier' or `static'
/w/foo.cs(7,4): error CS1525: Unexpected symbol `int', expecting `identifier' or `static'
/w/foo.cs(12,8): error CS1525: Unexpected symbol `sum', expecting `identifier' or `static'
/w/foo.cs(14,2): error CS1514: Unexpected symbol `}', expecting `.' or `{'

[Hydro](https://hydro.ac)提供评测服务