/tmp/ccU6brRC.o: In function `main':
ex3.c:(.text.startup+0x0): multiple definition of `main'
/tmp/ccRh3rqa.o:main.c:(.text.startup+0x0): first defined here
/tmp/ccRh3rqa.o: In function `main':
main.c:(.text.startup+0xb7): undefined reference to `ex3'
collect2: error: ld returned 1 exit status