View Compilation Error

0_0_18483692_4600.cpp: In function 'int main()':
0_0_18483692_4600.cpp:7:46: error: 'EFO' was not declared in this scope
 while(scanf("%lf%lf%lf%lf",&x1,&x2,&y1,&y2)!=EFO)
                                              ^