foo.cc: In function 'int main()':
foo.cc:102:22: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long long int' [-Wformat=]
         printf("%d",b);
                      ^
foo.cc:147:25: warning: 'st' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (st != tot2) dfs2(st,1);
                     ~~~~^~~~~~