c-gcc, 113 bytes

Result

ERROR

Code [DL]

char l[100],i,j;main(){for(i;i<100;i++){read(0,&j,1);l[j]++;}for(i=48;i<58;i++)for(j=0;j<l[i];j++)write(1,&i,1);}

stdin

6383047131521264534234214003447643821212567416474260822494234313134946526836604847526239265345973214

stdout

stderr

strace