foo.cc: In function 'void MergeSubs(int*, int)':
foo.cc:51:9: warning: unused variable 'n1_start' [-Wunused-variable]
     int n1_start=0,n1_end=0,n2_start=0,n2_end=0;
         ^~~~~~~~
foo.cc:51:20: warning: unused variable 'n1_end' [-Wunused-variable]
     int n1_start=0,n1_end=0,n2_start=0,n2_end=0;
                    ^~~~~~
foo.cc:51:29: warning: unused variable 'n2_start' [-Wunused-variable]
     int n1_start=0,n1_end=0,n2_start=0,n2_end=0;
                             ^~~~~~~~
foo.cc:51:40: warning: unused variable 'n2_end' [-Wunused-variable]
     int n1_start=0,n1_end=0,n2_start=0,n2_end=0;
                                        ^~~~~~

[Hydro](https://hydro.ac)提供评测服务