View Compilation Error

0_0_27194598_17212.cpp: In function 'll powmod(ll, ll)':
0_0_27194598_17212.cpp:16:60: error: 'assert' was not declared in this scope
 ll powmod(ll a, ll b) { ll res = 1; a %= mod; assert(b >= 0); for (; b; b >>= 1) { if (b & 1)res = res * a%mod; a = a * a%mod; }return res; }
                                                            ^
0_0_27194598_17212.cpp: In function 'int main()':
0_0_27194598_17212.cpp:69:29: error: 'sort' was not declared in this scope
   sort(q + 1, q + m + 1, cmp);
                             ^
0_0_27194598_17212.cpp:10:41: error: 'memset' was not declared in this scope
 #define mem(a, b) memset(a, b, sizeof(a))
                                         ^
0_0_27194598_17212.cpp:74:3: note: in expansion of macro 'mem'
   mem(gay, 0);
   ^