View Compilation Error

0_0_23804216_9462.cpp: In function 'int main()':
0_0_23804216_9462.cpp:14:37: error: 'w' was not declared in this scope
  for (int i=1;i<=n;i++) scanf("%d",&w[i]);
                                     ^
0_0_23804216_9462.cpp:20:17: error: 'assert' was not declared in this scope
  assert(num==n-1);
                 ^