c-gcc, 55 bytes

Result

WA

Duration

559ms

Code [DL]

main(i){for(;i<26;i++)putchar((getchar()+i-12)%26+64);}

stdin

QCFLENGIQZZCLNGUVQKRPCQIIF

stdout

REIPJTNQ@JKOYBVKMIDLKYNGH

stderr

/tmp/code.c:1:1: warning: return type defaults to 'int' [-Wimplicit-int]
 main(i){for(;i<26;i++)putchar((getchar()+i-12)%26+64);}
 ^~~~
/tmp/code.c: In function 'main':
/tmp/code.c:1:1: warning: type of 'i' defaults to 'int' [-Wimplicit-int]
/tmp/code.c:1:23: warning: implicit declaration of function 'putchar' [-Wimplicit-function-declaration]
 main(i){for(;i<26;i++)putchar((getchar()+i-12)%26+64);}
                       ^~~~~~~
/tmp/code.c:1:32: warning: implicit declaration of function 'getchar' [-Wimplicit-function-declaration]
 main(i){for(;i<26;i++)putchar((getchar()+i-12)%26+64);}
                                ^~~~~~~

strace