/in/foo.cc: In function 'int main()':
/in/foo.cc:25:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0;i<vec.size();i++)
             ~^~~~~~~~~~~
/in/foo.cc:6:18: warning: unused variable 'k' [-Wunused-variable]
    int na,nb,i,j,k=0,m;
                  ^
/in/foo.cc:6:22: warning: unused variable 'm' [-Wunused-variable]
    int na,nb,i,j,k=0,m;
                      ^