/in/foo.cc: In function 'int main()':
/in/foo.cc:32:34: warning: format '%d' expects argument of type 'int*', but argument 3 has type 'char*' [-Wformat=]
             scanf("%d%d", &a, &ch);
                               ~~~^
/in/foo.cc:50:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 while (a < v.size() && b < v.size())
                        ~~^~~~~~~~~~
/in/foo.cc:50:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 while (a < v.size() && b < v.size())
                                        ~~^~~~~~~~~~