/in/foo.cc: In function 'int main()':
/in/foo.cc:54:22: warning: 'tb' may be used uninitialized in this function [-Wmaybe-uninitialized]
   paixu(b,nb-(nb-tb));    
                      ^
/in/foo.cc:45:22: warning: 'ta' may be used uninitialized in this function [-Wmaybe-uninitialized]
   paixu(a,na-(na-ta));
                      ^