View Compilation Error

0_0_18297387_1768.cpp: In member function 'int Solution::countPrimes(int)':
0_0_18297387_1768.cpp:4:9: error: 'vector' was not declared in this scope
         vector<bool> num(n - 1, true);
         ^
0_0_18297387_1768.cpp:4:16: error: expected primary-expression before 'bool'
         vector<bool> num(n - 1, true);
                ^
0_0_18297387_1768.cpp:5:9: error: 'num' was not declared in this scope
         num[0] = false;
         ^
0_0_18297387_1768.cpp:6:36: error: 'sqrt' was not declared in this scope
         int res = 0, limit = sqrt(n);
                                    ^