portals.cpp: In function 'int bfs()':
portals.cpp:21:48: error: converting to 'std::deque<std::tuple<int, int, int, int> >::value_type {aka std::tuple<int, int, int, int>}' from initializer list would use explicit constructor 'constexpr std::tuple< <template-parameter-1-1> >::tuple(_UElements&& ...) [with _UElements = {int&, int&, int, int}; <template-parameter-2-2> = void; _Elements = {int, int, int, int}]'
q.push_back({start.first, start.second, 0, 0});
^
portals.cpp:48:39: error: converting to 'std::deque<std::tuple<int, int, int, int> >::value_type {aka std::tuple<int, int, int, int>}' from initializer list would use explicit constructor 'constexpr std::tuple< <template-parameter-1-1> >::tuple(_UElements&& ...) [with _UElements = {int&, int&, int&, int&}; <template-parameter-2-2> = void; _Elements = {int, int, int, int}]'
q.push_back({nx, ny, px, py});
^
portals.cpp:61:38: error: converting to 'std::deque<std::tuple<int, int, int, int> >::value_type {aka std::tuple<int, int, int, int>}' from initializer list would use explicit constructor 'constexpr std::tuple< <template-parameter-1-1> >::tuple(_UElements&& ...) [with _UElements = {int&, int&, int&, int&}; <template-parameter-2-2> = void; _Elements = {int, int, int, int}]'
q.push_front({x, y, nx, ny});
^
portals.cpp:69:35: error: converting to 'std::deque<std::tuple<int, int, int, int> >::value_type {aka std::tuple<int, int, int, int>}' from initializer list would use explicit constructor 'constexpr std::tuple< <template-parameter-1-1> >::tuple(_UElements&& ...) [with _UElements = {int&, int&, int&, int&}; <template-parameter-2-2> = void; _Elements = {int, int, int, int}]'
q.push_back({px, py, px, py});
^
portals.cpp: In function 'int main()':
portals.cpp:77:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &n, &m);
^
portals.cpp:81:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf(" %c", &c);
^