/in/foo.c:1:1: warning: data definition has no type or storage class
 r=input("input a number please")
 ^
/in/foo.c:1:1: warning: type defaults to 'int' in declaration of 'r' [-Wimplicit-int]
/in/foo.c:1:3: warning: implicit declaration of function 'input' [-Wimplicit-function-declaration]
 r=input("input a number please")
   ^~~~~
/in/foo.c:1:3: error: initializer element is not constant
/in/foo.c:2:2: error: expected ',' or ';' before 'v'
  v=4/3*PI*r*r*r
  ^