View Compilation Error

0_0_33802736_31770.cpp: In function 'void fun(int)':
0_0_33802736_31770.cpp:17:17: error: 'sqrt' was not declared in this scope
     int m=sqrt(x);
                 ^
0_0_33802736_31770.cpp: In function 'int check(int, int, int)':
0_0_33802736_31770.cpp:33:51: error: 'upper_bound' was not declared in this scope
     return upper_bound(v[x].begin(), v[x].end(), r) - lower_bound(v[x].begin(), v[x].end(), l);
                                                   ^
0_0_33802736_31770.cpp: In function 'int main()':
0_0_33802736_31770.cpp:56:25: error: 'sqrt' was not declared in this scope
             int m=sqrt(d);
                         ^