c-gcc, 123 bytes

Result

WA

Duration

613ms

Code [DL]

main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}

stdin

f2c7a7yyz9j3s7b2w8j2o6v2x9d7n9b3l7ca7a2u9g7t9zahi2pd4r2t5t9i4q5l5h8p5n3o3y7n3m5k4e2u9i6p2q8f9

stdout

stderr

/tmp/code.c:1:1: warning: return type defaults to 'int' [-Wimplicit-int]
 main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}
 ^~~~
/tmp/code.c: In function 'main':
/tmp/code.c:1:36: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
 main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}
                                    ^~~~~
/tmp/code.c:1:36: warning: incompatible implicit declaration of built-in function 'scanf'
/tmp/code.c:1:36: note: include '<stdio.h>' or provide a declaration of 'scanf'
+#include <stdio.h>
 main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}
                                    ^~~~~
/tmp/code.c:1:42: error: expected expression before '%' token
 main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}
                                          ^
/tmp/code.c:1:47: warning: left-hand operand of comma expression has no effect [-Wunused-value]
 main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}
                                               ^
/tmp/code.c:1:94: warning: the omitted middle operand in ?: will always be 'true', suggest explicit middle operand [-Wparentheses]
 main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}
                                                                                              ^
/tmp/code.c:1:103: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
 main(){char i[101];int b,c,d;for(b=scanf(%s,i),d=b;b;b--)if(i[d-b]-48>9)for(c=i[d-b-1]-48<=9?:1;c;c--)printf("%c",i[d-b]);}
                                                                                                       ^~~~~~
/tmp/code.c:1:103: warning: incompatible implicit declaration of built-in function 'printf'
/tmp/code.c:1:103: note: include '<stdio.h>' or provide a declaration of 'printf'
/root/script: line 7: /tmp/code: not found
rm: can't remove '/tmp/code': No such file or directory

strace