c-gcc, 96 bytes

Result

AC

Duration

628ms

Code [DL]

main(d,c,b){for(;c-10;){c=getchar();if(c>=65){d=c;putchar(c);}	else{for(;c>49;c--)putchar(d);}}}

stdin

k2a7y2n2m3cu6qm8g8em8p7pfmy4i7t8i5y9b6n4v4o3r7g4x7s3d3l4s6l3n6w4h6h3z5d2q2jw6l5d7b4a4vj3e9n3

stdout

kkaaaaaaayynnmmmcuuuuuuqmmmmmmmmggggggggemmmmmmmmppppppppfmyyyyiiiiiiittttttttiiiiiyyyyyyyyybbbbbbnnnnvvvvooorrrrrrrggggxxxxxxxsssdddllllsssssslllnnnnnnwwwwhhhhhhhhhzzzzzddqqjwwwwwwllllldddddddbbbbaaaavjjjeeeeeeeeennn

stderr

/tmp/code.c:1:1: warning: return type defaults to 'int' [-Wimplicit-int]
 main(d,c,b){for(;c-10;){c=getchar();if(c>=65){d=c;putchar(c);} else{for(;c>49;c--)putchar(d);}}}
 ^~~~
/tmp/code.c: In function 'main':
/tmp/code.c:1:1: warning: type of 'd' defaults to 'int' [-Wimplicit-int]
/tmp/code.c:1:1: warning: type of 'c' defaults to 'int' [-Wimplicit-int]
/tmp/code.c:1:1: warning: type of 'b' defaults to 'int' [-Wimplicit-int]
/tmp/code.c:1:27: warning: implicit declaration of function 'getchar' [-Wimplicit-function-declaration]
 main(d,c,b){for(;c-10;){c=getchar();if(c>=65){d=c;putchar(c);} else{for(;c>49;c--)putchar(d);}}}
                           ^~~~~~~
/tmp/code.c:1:27: note: 'getchar' is defined in header '<stdio.h>'; did you forget to '#include <stdio.h>'?
+#include <stdio.h>
 main(d,c,b){for(;c-10;){c=getchar();if(c>=65){d=c;putchar(c);} else{for(;c>49;c--)putchar(d);}}}
                           ^~~~~~~
/tmp/code.c:1:51: warning: implicit declaration of function 'putchar' [-Wimplicit-function-declaration]
 main(d,c,b){for(;c-10;){c=getchar();if(c>=65){d=c;putchar(c);} else{for(;c>49;c--)putchar(d);}}}
                                                   ^~~~~~~

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