View Compilation Error

0_0_35355938_18893.cpp: In function 'int bfs()':
0_0_35355938_18893.cpp:91:46: error: 'abs' was not declared in this scope
             if ( abs( map[p.x][p.y][p.state] ) < 3 && map[p.x][p.y][p.state] > 0 ) continue;
                                              ^