/in/foo.c: In function 'main':
/in/foo.c:5:3: warning: implicit declaration of function 'input' [-Wimplicit-function-declaration]
   input("%d%d",&a,&b);
   ^~~~~
/tmp/ccZ2squd.o: In function `main':
foo.c:(.text.startup+0x18): undefined reference to `input'
collect2: error: ld returned 1 exit status