/in/foo.cc: In function 'int main()':
/in/foo.cc:66:14: warning: 'b2' may be used uninitialized in this function [-Wmaybe-uninitialized]
         a=crt(a1,w1,b2,w2),b=crt(b1,w1,a2,w2);
           ~~~^~~~~~~~~~~~~
/in/foo.cc:59:13: warning: 'a2' may be used uninitialized in this function [-Wmaybe-uninitialized]
     ll a=crt(a1,w1,a2,w2),b=crt(b1,w1,b2,w2);
          ~~~^~~~~~~~~~~~~
/in/foo.cc:59:32: warning: 'b1' may be used uninitialized in this function [-Wmaybe-uninitialized]
     ll a=crt(a1,w1,a2,w2),b=crt(b1,w1,b2,w2);
                             ~~~^~~~~~~~~~~~~
/in/foo.cc:66:14: warning: 'a1' may be used uninitialized in this function [-Wmaybe-uninitialized]
         a=crt(a1,w1,b2,w2),b=crt(b1,w1,a2,w2);
           ~~~^~~~~~~~~~~~~