delete iostream and using namespace std.
all cin cout replace on scanf and pritf
write in start of code: #define CRT_SECURE_NO_WARNINGS
and #include<cstdio>
and behind your vectors,pair and queue write std::
do vector WITHOUT ANY INTS, ALL BOOL
DONT USE PUSH_BACK its really slow, just write size of vector
Example:
>std::vector<std::vector<bool>> a(n);
>std::vector<bool> b(m);
and call with a[i][j] or something else;
If you look at other aspects of the task, then EASY BFS