View Compilation Error

0_0_37906643_2646.cpp: In function 'int main()':
0_0_37906643_2646.cpp:6:31: error: 'x_1' was not declared in this scope
   while(~scanf("%d %d %d %d",&x_1 ,&y_1 ,&x_2 ,&y_2)
                               ^
0_0_37906643_2646.cpp:6:43: error: 'x_2' was not declared in this scope
   while(~scanf("%d %d %d %d",&x_1 ,&y_1 ,&x_2 ,&y_2)
                                           ^
0_0_37906643_2646.cpp:7:4: error: expected ')' before '{' token
    {
    ^
0_0_37906643_2646.cpp:8:68: error: expression cannot be used as a function
       int ans = sqrt((x_1 - x_2)(x_1 - X_2) + (y_1 - y_2)(y_1 - y_2))
                                                                    ^
0_0_37906643_2646.cpp:10:4: error: expected ',' or ';' before '}' token
    }
    ^