/in/foo.cc: In function 'int main()':
/in/foo.cc:13:9: warning: unused variable 'k' [-Wunused-variable]
  double k,a,b,c,min;
         ^
/in/foo.cc:59:29: warning: 's2' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<num[s1]<<endl<<num[s2]<<endl;
                             ^
/in/foo.cc:59:14: warning: 's1' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<num[s1]<<endl<<num[s2]<<endl;
              ^