View Compilation Error

0_0_36473742_1862.cpp: In function 'void Union(int, int)':
0_0_36473742_1862.cpp:9:5: error: 'fa' was not declared in this scope
     fa[Find(y)] = Find(x);
     ^
0_0_36473742_1862.cpp: In function 'int main()':
0_0_36473742_1862.cpp:16:38: error: 'fa' was not declared in this scope
         for(int i = 1; i <= n; i ++) fa[i] = i;//初始化并查集
                                      ^
0_0_36473742_1862.cpp:23:16: error: 'fa' was not declared in this scope
             if(fa[i] == i) ans ++;
                ^