/in/foo.cc: In function 'int main()':
/in/foo.cc:46:11: warning: suggest parentheses around comparison in operand of '==' [-Wparentheses]
       if(w==x==y==z)
          ~^~~
/in/foo.cc:46:14: warning: suggest parentheses around comparison in operand of '==' [-Wparentheses]
       if(w==x==y==z)
          ~~~~^~~
/in/foo.cc:35:6: warning: 'w' may be used uninitialized in this function [-Wmaybe-uninitialized]
     w+=a[j];
     ~^~~~~~