View Compilation Error

0_0_29933447_11224.cpp: In function 'int main()':
0_0_29933447_11224.cpp:32:15: error: 'y0' was not declared in this scope
         db x0=y0=1;
               ^
0_0_29933447_11224.cpp:40:13: error: 'step' was not declared in this scope
             step+=dis;
             ^