Language: C

y,m,e;main(z){
	for(;m=scanf("%d",&e)*e;y=!printf("%d\n",m))
		for(;z=cbrt(e+=~y+y),k>=0;m=fmin(m,e-z*z*z+z+y++));
}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | y,m,e;main(z){
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 'y' [-Wimplicit-int]
main.c:1:3: error: type defaults to 'int' in declaration of 'm' [-Wimplicit-int]
    1 | y,m,e;main(z){
      |   ^
main.c:1:5: error: type defaults to 'int' in declaration of 'e' [-Wimplicit-int]
    1 | y,m,e;main(z){
      |     ^
main.c:1:7: error: return type defaults to 'int' [-Wimplicit-int]
    1 | y,m,e;main(z){
      |       ^~~~
main.c: In function 'main':
main.c:1:7: error: type of 'z' defaults to 'int' [-Wimplicit-int]
main.c:2:16: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    2 |         for(;m=scanf("%d",&e)*e;y=!printf("%d\n",m))
      |                ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | y,m,e;main(z){
main.c:2:16: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    2 |         for(;m=scanf("%d",&e)*e;y=!printf("%d\n",m))
      |                ^~~~~
main.c:2:16: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:2:36: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    2 |         for(;m=scanf("%d",&e)*e;y=!printf("%d\n",m))
      |                                    ^~~~~~
main.c:2:36: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:2:36: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:2:36: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:3:24: error: implicit declaration of function 'cbrt' [-Wimplicit-function-declaration]
    3 |                 for(;z=cbrt(e+=~y+y),k>=0;m=fmin(m,e-z*z*z+z+y++));
      |                        ^~~~
main.c:1:1: note: include '<math.h>' or provide a declaration of 'cbrt'
  +++ |+#include <math.h>
    1 | y,m,e;main(z){
main.c:3:24: warning: incompatible implicit declaration of built-in function 'cbrt' [-Wbuiltin-declaration-mismatch]
    3 |                 for(;z=cbrt(e+=~y+y),k>=0;m=fmin(m,e-z*z*z+z+y++));
      |                        ^~~~
main.c:3:24: note: include '<math.h>' or provide a declaration of 'cbrt'
main.c:3:38: error: 'k' undeclared (first use in this function)
    3 |                 for(;z=cbrt(e+=~y+y),k>=0;m=fmin(m,e-z*z*z+z+y++));
      |                                      ^
main.c:3:38: note: each undeclared identifier is reported only once for each function it appears in
main.c:3:45: error: implicit declaration of function 'fmin' [-Wimplicit-function-declaration]
    3 |                 for(;z=cbrt(e+=~y+y),k>=0;m=fmin(m,e-z*z*z+z+y++));
      |                                             ^~~~
main.c:3:45: note: include '<math.h>' or provide a declaration of 'fmin'
main.c:3:45: warning: incompatible implicit declaration of built-in function 'fmin' [-Wbuiltin-declaration-mismatch]
main.c:3:45: note: include '<math.h>' or provide a declaration of 'fmin'