/in/foo.cc: In function 'int main()':
/in/foo.cc:51:11: warning: unused variable 'j' [-Wunused-variable]
     int i,j,k;
           ^
/in/foo.cc:51:13: warning: unused variable 'k' [-Wunused-variable]
     int i,j,k;
             ^
/in/foo.cc:78:33: warning: 'e' may be used uninitialized in this function [-Wmaybe-uninitialized]
   double r=(d==0||e==0)?0:(1.0*d*e)/(d+e);
                           ~~~~~~^~~
/in/foo.cc:78:33: warning: 'd' may be used uninitialized in this function [-Wmaybe-uninitialized]
/in/foo.cc:79:6: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   r+=c;
      ^
/in/foo.cc:80:26: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   r=(r==0||b==0)?0:(1.0*r*b)/(r+b);
                    ~~~~~~^~~
/in/foo.cc:81:6: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   r+=a;
      ^