View Compilation Error

0_0_31940812_22707.cpp: In function 'int main()':
0_0_31940812_22707.cpp:5:27: error: 'scanf' was not declared in this scope
     scanf("%f %f ",&x1,&x2);
                           ^
0_0_31940812_22707.cpp:6:16: error: 'printf' was not declared in this scope
     printf("\n");
                ^
0_0_31940812_22707.cpp:9:24: error: 'sqrt' was not declared in this scope
     d1=sqrt(x1*x1+y1*y1);
                        ^