View Compilation Error

0_0_30673513_28596.cpp: In function 'int main()':
0_0_30673513_28596.cpp:5:37: error: 'scanf' was not declared in this scope
     scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
                                     ^
0_0_30673513_28596.cpp:8:22: error: 'printf' was not declared in this scope
     printf("%f\n",sum);
                      ^