View Compilation Error

0_0_21484730_4348.cpp: In function 'void init()':
0_0_21484730_4348.cpp:19:34: error: 'memset' was not declared in this scope
     memset(head, -1, sizeof(head));
                                  ^
0_0_21484730_4348.cpp: In function 'int main()':
0_0_21484730_4348.cpp:44:33: error: 'scanf' was not declared in this scope
     while (~scanf("%d%d", &n, &k))
                                 ^
0_0_21484730_4348.cpp:58:37: error: 'min' was not declared in this scope
             ans += (LL)min(sum[i], k) * w[i];
                                     ^
0_0_21484730_4348.cpp:60:29: error: 'printf' was not declared in this scope
         printf("%lld\n", ans);
                             ^