foo.cc: In function 'int main()':
foo.cc:23:37: warning: 'a4' may be used uninitialized in this function [-Wmaybe-uninitialized]
   23 |         a[1]=a1,a[2]=a2,a[3]=a3,a[4]=a4;
      |                                 ~~~~^~~
foo.cc:23:29: warning: 'a3' may be used uninitialized in this function [-Wmaybe-uninitialized]
   23 |         a[1]=a1,a[2]=a2,a[3]=a3,a[4]=a4;
      |                         ~~~~^~~
foo.cc:23:21: warning: 'a2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   23 |         a[1]=a1,a[2]=a2,a[3]=a3,a[4]=a4;
      |                 ~~~~^~~
foo.cc:23:13: warning: 'a1' may be used uninitialized in this function [-Wmaybe-uninitialized]
   23 |         a[1]=a1,a[2]=a2,a[3]=a3,a[4]=a4;
      |         ~~~~^~~

[Hydro](https://hydro.ac)提供评测服务