/in/foo.cc: In function 'int main()':
/in/foo.cc:36:9: warning: unused variable 'n1' [-Wunused-variable]
 int num,n1,n2,L,k,n;
         ^~
/in/foo.cc:61:10: warning: 'num' may be used uninitialized in this function [-Wmaybe-uninitialized]
 cout<<num;
          ^