View Compilation Error

0_0_15305342_21411.cpp: In function 'int main()':
0_0_15305342_21411.cpp:6:15: error: too few arguments to function 'int scanf(const char*, ...)'
   while(scanf()!=EOF)
               ^
In file included from 0_0_15305342_21411.cpp:1:0:
GCC4.9.2/x86_64-w64-mingw32/include/stdio.h:386:15: note: declared here
   int __cdecl scanf(const char * __restrict__ _Format,...) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
               ^
0_0_15305342_21411.cpp:8:44: error: 'sqrt' was not declared in this scope
    l=sqrt(((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)))
                                            ^