View Compilation Error

0_0_19980645_25259.cpp: In function 'int main()':
0_0_19980645_25259.cpp:6:24: error: expected unqualified-id before ',' token
      float x1,x2,y1,y2,,s;
                        ^
0_0_19980645_25259.cpp:9:6: error: 'a' was not declared in this scope
      a=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}
      ^
0_0_19980645_25259.cpp:9:44: error: 'sqrt' was not declared in this scope
      a=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}
                                            ^
0_0_19980645_25259.cpp:10:12: error: 'a' was not declared in this scope
      cout<<a<<setprecision(2);
            ^