prog.c:3:5: warning: conflicting types for built-in function ‘pow’
int pow(int base, int n)
^~~
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status