Runtime Error
/in/foo.cc: In function 'void build(int, int, int)':
/in/foo.cc:15:18: warning: statement has no effect [-Wunused-value]
tr[p].l=l;tr[p].r;
~~~~~~^
/in/foo.cc: In function 'void build(int, int, int)':
/in/foo.cc:15:18: warning: statement has no effect [-Wunused-value]
tr[p].l=l;tr[p].r;
~~~~~~^
