View Compilation Error

0_0_25421777_32102.cpp:9:7: error: 'maxn' does not name a type
 const maxn=50010;
       ^
0_0_25421777_32102.cpp:10:10: error: 'maxn' was not declared in this scope
 double x[maxn],y[maxn];
          ^
0_0_25421777_32102.cpp:10:18: error: 'maxn' was not declared in this scope
 double x[maxn],y[maxn];
                  ^
0_0_25421777_32102.cpp: In function 'double f(double)':
0_0_25421777_32102.cpp:17:22: error: 'x' was not declared in this scope
         temp=sqrt((a-x[i])*(a-x[i])+y[i]*y[i]);
                      ^
0_0_25421777_32102.cpp:17:37: error: 'y' was not declared in this scope
         temp=sqrt((a-x[i])*(a-x[i])+y[i]*y[i]);
                                     ^
0_0_25421777_32102.cpp: In function 'int main()':
0_0_25421777_32102.cpp:27:31: error: 'x' was not declared in this scope
             scanf("%lf %lf", &x[i], &y[i]);
                               ^
0_0_25421777_32102.cpp:27:38: error: 'y' was not declared in this scope
             scanf("%lf %lf", &x[i], &y[i]);
                                      ^