foo.cpp:7:7: error: 'MAXN' was not declared in this scope
 int a[MAXN], f[MAXN], visit[MAXN], d, step[MAXN];
       ^
foo.cpp:7:16: error: 'MAXN' was not declared in this scope
 int a[MAXN], f[MAXN], visit[MAXN], d, step[MAXN];
                ^
foo.cpp:7:29: error: 'MAXN' was not declared in this scope
 int a[MAXN], f[MAXN], visit[MAXN], d, step[MAXN];
                             ^
foo.cpp:7:44: error: 'MAXN' was not declared in this scope
 int a[MAXN], f[MAXN], visit[MAXN], d, step[MAXN];
                                            ^
foo.cpp:9:11: error: 'MAXN' was not declared in this scope
 bool flag[MAXN], okay;
           ^
foo.cpp: In function 'int main()':
foo.cpp:13:9: error: 'flag' was not declared in this scope
  memset(flag, 0, sizeof(flag));
         ^
foo.cpp:14:9: error: 'f' was not declared in this scope
  memset(f, 0, sizeof(f));
         ^
foo.cpp:15:9: error: 'step' was not declared in this scope
  memset(step, 0, sizeof(step));
         ^
foo.cpp:16:8: error: 'MAXN' was not declared in this scope
  ans = MAXN;
        ^
foo.cpp:21:10: error: 'a' was not declared in this scope
   cin >> a[i];
          ^
foo.cpp:30:8: error: 'visit' was not declared in this scope
    d = visit[0] = i;
        ^
foo.cpp:33:17: error: 'a' was not declared in this scope
    while (!flag[a[d]]) {
                 ^
foo.cpp:40:24: error: 'a' was not declared in this scope
     if (visit[head] == a[d])
                        ^