/in/foo.cc: In function 'int main()':
/in/foo.cc:6:12: warning: unused variable 'ans' [-Wunused-variable]
  int i,n,j,ans,l,r,len=1;
            ^~~
/in/foo.cc:6:16: warning: unused variable 'l' [-Wunused-variable]
  int i,n,j,ans,l,r,len=1;
                ^
/in/foo.cc:6:18: warning: unused variable 'r' [-Wunused-variable]
  int i,n,j,ans,l,r,len=1;
                  ^