View Compilation Error

0_0_15339481_32738.cpp:8:4: error: 'MAXN' was not declared in this scope
 }P[MAXN];
    ^
0_0_15339481_32738.cpp: In function 'int main()':
0_0_15339481_32738.cpp:17:47: error: 'P' was not declared in this scope
         for(int i=1; i<=n; i++) scanf("%d%d",&P[i].x,&P[i].y);
                                               ^
0_0_15339481_32738.cpp:27:33: error: 'P' was not declared in this scope
                 D.push_back(Dot(P[i]-P[j],P[i]-P[j]));
                                 ^
0_0_15339481_32738.cpp:27:52: error: 'Dot' was not declared in this scope
                 D.push_back(Dot(P[i]-P[j],P[i]-P[j]));
                                                    ^