#0  0xb75876f3 in std::_Rb_tree_rebalance_for_erase ()
   from /usr/lib/libstdc++.so.6
#1  0x0807165b in ?? ()
#2  0x08071738 in ?? ()
#3  0x0807133f in ?? ()
#4  0xb73e79d9 in exit () from /lib/tls/i686/cmov/libc.so.6
#5  0xb73d0ec4 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#6  0x0805c431 in ?? ()