/in/foo.c:1:1: warning: data definition has no type or storage class
 a=int(input("请输入一个自然数"))
 ^
/in/foo.c:1:1: warning: type defaults to 'int' in declaration of 'a' [-Wimplicit-int]
/in/foo.c:1:3: error: expected expression before 'int'
 a=int(input("请输入一个自然数"))
   ^~~
/in/foo.c:2:13: warning: missing terminating " character
 b=int(input("请输入另一个自然数))
             ^
/in/foo.c:2:13: error: missing terminating " character
 b=int(input("请输入另一个自然数))
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~