foo.c:1:1: warning: data definition has no type or storage class
 a=input()
 ^
foo.c:1:1: warning: type defaults to 'int' in declaration of 'a' [-Wimplicit-int]
foo.c:1:3: warning: implicit declaration of function 'input' [-Wimplicit-function-declaration]
 a=input()
   ^~~~~
foo.c:1:3: error: initializer element is not constant
foo.c:2:1: error: expected ',' or ';' before 'result'
 result=(a-2000)/1000
 ^~~~~~

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