View Compilation Error

0_0_37661866_19264.cpp:1:1: error: 'include' does not name a type
 include <bits/stdc++.h>
 ^
0_0_37661866_19264.cpp:5:9: error: 'pair' does not name a type
 typedef pair<int,int> pii;
         ^
0_0_37661866_19264.cpp: In function 'int main()':
0_0_37661866_19264.cpp:20:49: error: 'scanf' was not declared in this scope
     while (~scanf("%d%d%d%d", &x1, &y1, &x2, &y2)) {
                                                 ^
0_0_37661866_19264.cpp:23:37: error: 'sqrt' was not declared in this scope
      printf("%.2f\n", sqrt(a*a + b*b));
                                     ^
0_0_37661866_19264.cpp:23:38: error: 'printf' was not declared in this scope
      printf("%.2f\n", sqrt(a*a + b*b));
                                      ^