/in/foo.cc: In function 'int main()':
/in/foo.cc:7:20: error: 'sqrt' was not declared in this scope
  double t1=sqrt(h/5),t2=sqrt((h-k)/5);
                    ^
/in/foo.cc:8:16: error: 't2' was not declared in this scope
  int ii=int(s1-t2*v+l),i=int(s1-t1*v);
                ^~
/in/foo.cc:9:16: error: 'i' was not declared in this scope
  ii=min(ii,n); i=max(i,0);
                ^
/in/foo.cc:7:9: warning: unused variable 't1' [-Wunused-variable]
  double t1=sqrt(h/5),t2=sqrt((h-k)/5);
         ^~