/in/foo.cc: In function 'int BFS()':
/in/foo.cc:41:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
              for(int ka=0;ka<g[a].size();ka++){ 
                           ~~^~~~~~~~~~~~
/in/foo.cc:52:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
              for(int kb=0;kb<g[b].size();kb++){ 
                           ~~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:71:25: warning: format '%d' expects argument of type 'int', but argument 2 has type 'int (*)()' [-Wformat=]
        printf("%d\n",BFS);    
                         ^