View Compilation Error

0_0_20696900_20717.cpp: In function 'int main()':
0_0_20696900_20717.cpp:68:32: error: 'y0' was not declared in this scope
         scanf("%d%d%d%d%d",&k,&y0,&x1,&y2,&x2);//注意他说的行列和常规的想法不一样，免得自己搞混，所以我先输入的y。  
                                ^