c-gcc, 74 bytes

Result

WA

Code [DL]

f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}

stdin

9204319687806157147030542404174903149957675285534517427724131808735894770887940250324774408674312592

stdout

2952134768044774230520497880774985378081314277247154355825767599413094714042450307417516087869134029

stderr

/volume/CODE.c:1:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
 ^
/volume/CODE.c: In function ‘f’:
/volume/CODE.c:1:19: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
                   ^
/volume/CODE.c: At top level:
/volume/CODE.c:1:27: warning: data definition has no type or storage class
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
                           ^
/volume/CODE.c:1:27: warning: type defaults to ‘int’ in declaration of ‘s’ [-Wimplicit-int]
/volume/CODE.c:1:34: warning: return type defaults to ‘int’ [-Wimplicit-int]
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
                                  ^
/volume/CODE.c: In function ‘main’:
/volume/CODE.c:1:41: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-declaration]
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
                                         ^
/volume/CODE.c:1:49: warning: implicit declaration of function ‘qsort’ [-Wimplicit-function-declaration]
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
                                                 ^
/volume/CODE.c:1:66: warning: implicit declaration of function ‘puts’ [-Wimplicit-function-declaration]
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
                                                                  ^
/volume/CODE.c: In function ‘f’:
/volume/CODE.c:1:1: warning: control reaches end of non-void function [-Wreturn-type]
 f(char*a,char*b){a=*a-*b;}s[100];main(){gets(s);qsort(s,100,1,f);puts(s);}
 ^
/tmp/cc1AOHnr.o: In function `main':
CODE.c:(.text.startup+0xc): warning: the `gets' function is dangerous and should not be used.

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