other: sum.o extfun2.o
    gcc -o final sum.o extfun2.o

final: sum.o extfun.o
    gcc -o final sum.o extfun.o

sum.o: sum.c
    gcc -c -Wall -Werror -pedantic sum.c

extfun.o: extfun.c
    gcc -c -Wall -Werror -pedantic extfun.c

extfun2.o: extfun2.c
    gcc -c -Wall -Werror -pedantic extfun2.c