foo.cpp: In function 'int dfs(int)':
foo.cpp:41:20: warning: unused variable 'x2' [-Wunused-variable]
             double x2 = pigs[i].first, y2 = pigs[i].second;
                    ^~
foo.cpp:41:40: warning: unused variable 'y2' [-Wunused-variable]
             double x2 = pigs[i].first, y2 = pigs[i].second;
                                        ^~
foo.cpp: In function 'int main()':
foo.cpp:116:13: warning: unused variable 'j' [-Wunused-variable]
      int i, j;
             ^