foo.c: In function 'main':
foo.c:6:3: warning: implicit declaration of function 'sacnf'; did you mean 'sscanf'? [-Wimplicit-function-declaration]
   sacnf("%d%d%d",&a[i])
   ^~~~~
   sscanf
foo.c:7:2: error: expected ';' before 'for'
  for(int i=1; i<3; i++)
  ^~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。