/in/foo.c: In function 'fact':
/in/foo.c:5:24: warning: implicit declaration of function 'sqir' [-Wimplicit-function-declaration]
    5 |         for(int i=2;i<=sqir(n);i++)
      |                        ^~~~
/usr/bin/ld: /tmp/cchMTpGr.o: in function `fact':
foo.c:(.text+0x21): undefined reference to `sqir'
collect2: error: ld returned 1 exit status