View Compilation Error

0_0_35955567_28501.cpp: In function 'int main()':
0_0_35955567_28501.cpp:3:18: error: 'scanf' was not declared in this scope
     scanf("%d",&T);
                  ^
0_0_35955567_28501.cpp:11:46: error: 'abs' was not declared in this scope
         printf("%d\n",(int)floor(sqrt(abs(a-b))));
                                              ^
0_0_35955567_28501.cpp:11:47: error: 'sqrt' was not declared in this scope
         printf("%d\n",(int)floor(sqrt(abs(a-b))));
                                               ^
0_0_35955567_28501.cpp:11:48: error: 'floor' was not declared in this scope
         printf("%d\n",(int)floor(sqrt(abs(a-b))));
                                                ^
0_0_35955567_28501.cpp:11:49: error: 'printf' was not declared in this scope
         printf("%d\n",(int)floor(sqrt(abs(a-b))));
                                                 ^