c-gcc, 119 bytes

Result

WA

Duration

630ms

Code [DL]

main(){char i[101];int b,c,d;for(b=gets(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

j2l7tb2mc9z3t9s3f8tq6y3v4x5r8l8e2e5u5h7ob8p8n7r9w2ehwy8i5d9p5x4l8z8v9n5h7a9g4n6b5k9w2c4y9f2a6

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=gets(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 'gets' [-Wimplicit-function-declaration]
 main(){char i[101];int b,c,d;for(b=gets(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:1:90: 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=gets(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:1:99: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
 main(){char i[101];int b,c,d;for(b=gets(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:1:99: warning: incompatible implicit declaration of built-in function 'printf'
/tmp/code.c:1:99: note: include '<stdio.h>' or provide a declaration of 'printf'
+#include <stdio.h>
 main(){char i[101];int b,c,d;for(b=gets(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]);}
                                                                                                   ^~~~~~
Segmentation fault (core dumped)

strace