c-gcc, 53 bytes

Result

WA

Code [DL]

s[100];main(){gets(s);qsort(s,100,1,strcmp);puts(s);}

stdin

3181593034385351469157405188609448080502476215093339073007078220797652092112323185365859835622841893

stdout

stderr

/volume/CODE.c:1:1: warning: data definition has no type or storage class
 s[100];main(){gets(s);qsort(s,100,1,strcmp);puts(s);}
 ^
/volume/CODE.c:1:1: warning: type defaults to ‘int’ in declaration of ‘s’ [-Wimplicit-int]
/volume/CODE.c:1:8: warning: return type defaults to ‘int’ [-Wimplicit-int]
 s[100];main(){gets(s);qsort(s,100,1,strcmp);puts(s);}
        ^
/volume/CODE.c: In function ‘main’:
/volume/CODE.c:1:15: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-declaration]
 s[100];main(){gets(s);qsort(s,100,1,strcmp);puts(s);}
               ^
/volume/CODE.c:1:23: warning: implicit declaration of function ‘qsort’ [-Wimplicit-function-declaration]
 s[100];main(){gets(s);qsort(s,100,1,strcmp);puts(s);}
                       ^
/volume/CODE.c:1:37: error: ‘strcmp’ undeclared (first use in this function)
 s[100];main(){gets(s);qsort(s,100,1,strcmp);puts(s);}
                                     ^
/volume/CODE.c:1:37: note: each undeclared identifier is reported only once for each function it appears in
/volume/CODE.c:1:45: warning: implicit declaration of function ‘puts’ [-Wimplicit-function-declaration]
 s[100];main(){gets(s);qsort(s,100,1,strcmp);puts(s);}
                                             ^
/home/esolang/bin/c-gcc: line 4: /tmp/code: No such file or directory

strace