/in/foo.cc: In function 'int main()':
/in/foo.cc:31:11: warning: unused variable 'j' [-Wunused-variable]
   for(int j,i=1;i<=N;i++){
           ^
/in/foo.cc:45:23: warning: unused variable 'q' [-Wunused-variable]
     int j=i+len-1,p=j,q;
                       ^