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