/in/foo.cc: In function 'int main()':
/in/foo.cc:13:9: warning: 'z' may be used uninitialized [-Wmaybe-uninitialized]
   13 |         if(z==n)
      |         ^~
/in/foo.cc:5:19: note: 'z' was declared here
    5 |         int n,s=0,z;
      |                   ^