View Compilation Error

0_0_18050823_19849.cpp: In function 'void solve(int)':
0_0_18050823_19849.cpp:39:32: error: 'ch' was not declared in this scope
             while(m>1 && cross(ch[m-2],ch[m-1],node[i]))
                                ^
0_0_18050823_19849.cpp:41:41: error: 'ch' was not declared in this scope
             ans[-node[i].h] += getangle(ch[m-1],node[i]);
                                         ^
0_0_18050823_19849.cpp:44:24: error: 'ch' was not declared in this scope
             while(m && ch[m-1].h <= node[i].h)
                        ^
0_0_18050823_19849.cpp:46:32: error: 'ch' was not declared in this scope
             while(m>1 && cross(ch[m-2],ch[m-1],node[i]))
                                ^
0_0_18050823_19849.cpp:48:13: error: 'ch' was not declared in this scope
             ch[m++] = node[i];
             ^