Language: C

y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+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,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |   ^
main.c:1:5: error: type defaults to 'int' in declaration of 'z' [-Wimplicit-int]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |     ^
main.c:1:7: error: return type defaults to 'int' [-Wimplicit-int]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |       ^~~~
main.c: In function 'main':
main.c:1:7: error: type of 'e' defaults to 'int' [-Wimplicit-int]
main.c:1:22: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |                      ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
main.c:1:22: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |                      ^~~~~
main.c:1:22: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:42: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |                                          ^~~~~~
main.c:1:42: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:42: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:42: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:66: error: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |                                                                  ^~~~
main.c:1:1: note: include '<math.h>' or provide a declaration of 'sqrt'
  +++ |+#include <math.h>
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
main.c:1:66: warning: incompatible implicit declaration of built-in function 'sqrt' [-Wbuiltin-declaration-mismatch]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |                                                                  ^~~~
main.c:1:66: note: include '<math.h>' or provide a declaration of 'sqrt'
main.c:1:82: error: 'k' undeclared (first use in this function)
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |                                                                                  ^
main.c:1:82: note: each undeclared identifier is reported only once for each function it appears in
main.c:1:89: error: implicit declaration of function 'fmin' [-Wimplicit-function-declaration]
    1 | y,m,z;main(e){for(;m=scanf("%d",&e)*e;z=!printf("%d\n",m))for(;y=sqrt(e+=3*z*~z),k>=0;m=fmin(m,e--+y-y*y+z++));}
      |                                                                                         ^~~~
main.c:1:89: note: include '<math.h>' or provide a declaration of 'fmin'
main.c:1:89: warning: incompatible implicit declaration of built-in function 'fmin' [-Wbuiltin-declaration-mismatch]
main.c:1:89: note: include '<math.h>' or provide a declaration of 'fmin'