View Compilation Error

0_0_27206612_209.cpp: In function 'int main()':
0_0_27206612_209.cpp:5:37: error: 'scanf' was not declared in this scope
  scanf("%d %d %d %d",&x1,&y1,&x2,&y2);
                                     ^
0_0_27206612_209.cpp:6:37: error: 'sqrt' was not declared in this scope
  distance = sqrt((x1-x2)^2+(y1-y2)^2);
                                     ^
0_0_27206612_209.cpp:7:24: error: 'printf' was not declared in this scope
  printf("%.2f",distance);
                        ^