View Compilation Error

0_0_13109728_32618.cpp:1:1: error: 'include' does not name a type
 include<stdio.h>
 ^
0_0_13109728_32618.cpp: In function 'int main()':
0_0_13109728_32618.cpp:6:47: error: 'scanf' was not declared in this scope
  while(scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2)!=EOF)
                                               ^
0_0_13109728_32618.cpp:6:50: error: 'EOF' was not declared in this scope
  while(scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2)!=EOF)
                                                  ^
0_0_13109728_32618.cpp:10:21: error: 'printf' was not declared in this scope
   printf("%.2lf\n",b);
                     ^