View Compilation Error

0_0_38400703_27245.cpp:21:4: error: 'maxn' was not declared in this scope
 }p[maxn];
    ^
0_0_38400703_27245.cpp: In function 'int main()':
0_0_38400703_27245.cpp:40:18: error: 'p' was not declared in this scope
             cin>>p[i].x>>p[i].y;
                  ^
0_0_38400703_27245.cpp:43:14: error: 'p' was not declared in this scope
         sort(p,p+3*n,cmp);
              ^