View Compilation Error

0_0_35742816_12177.cpp: In function 'int main()':
0_0_35742816_12177.cpp:5:51: error: 'scanf' was not declared in this scope
     while (scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2)!=EOF) {
                                                   ^
0_0_35742816_12177.cpp:5:54: error: 'EOF' was not declared in this scope
     while (scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2)!=EOF) {
                                                      ^
0_0_35742816_12177.cpp:7:23: error: 'sqrt' was not declared in this scope
         sum=sqrt(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                       ^
0_0_35742816_12177.cpp:8:29: error: 'printf' was not declared in this scope
         printf("%.2lf\n",sum);
                             ^