foo.c:1:1: error: unknown type name 'using'
 using System;
 ^~~~~
foo.c:2:1: error: unknown type name 'using'
 using System.Collections.Generic;
 ^~~~~
foo.c:2:13: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token
 using System.Collections.Generic;
             ^
foo.c:3:1: error: unknown type name 'using'
 using System.Linq;
 ^~~~~
foo.c:3:13: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token
 using System.Linq;
             ^
foo.c:4:1: error: unknown type name 'using'
 using System.Text;
 ^~~~~
foo.c:4:13: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token
 using System.Text;
             ^
foo.c:5:1: error: unknown type name 'using'
 using System.Threading.Tasks;
 ^~~~~
foo.c:5:13: error: expected '=', ',', ';', 'asm' or '__attribute__' before '.' token
 using System.Threading.Tasks;
             ^
foo.c:7:1: error: unknown type name 'namespace'
 namespace ConsoleApp1
 ^~~~~~~~~
foo.c:8:1: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
 {
 ^

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