Main.c: In function 'main':
Main.c:4:13: warning: implicit declaration of function 'power' [-Wimplicit-function-declaration]
    4 | double sum=(power(2,64)-1);
      |             ^~~~~
/usr/lib/gcc/x86_64-alpine-linux-musl/12.2.1/../../../../x86_64-alpine-linux-musl/bin/ld: /tmp/ccChDikD.o: in function `main':
Main.c:(.text.startup+0x19): undefined reference to `power'
collect2: error: ld returned 1 exit status