/in/foo.cc: In function 'void bfs(int)':
/in/foo.cc:18:22: error: unable to find numeric literal operator 'operator""xc'
    if(tx==t)map[tx]=-1xc;
                      ^~~
/in/foo.cc:18:22: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes