/in/foo.cc: In function 'int main()':
/in/foo.cc:23:22: warning: operation on 'm' may be undefined [-Wsequence-point]
   23 |         while(cin>>a[++m].x>>a[m].y>>a[m].z){
      |                      ^~~
/in/foo.cc:23:22: warning: operation on 'm' may be undefined [-Wsequence-point]