Language: C++

#include <iostream>
#include <queue>
using namespace std;
typedef pair<int,int> P;

#define INF 1000000

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int d[1100][1100];
char store[1100][1100];

bool bfs(int w,int h,int sy,int sx,int gy,int gx){
	queue<P> que;
	d[sy][sx]=0;
	que.push(P(sy,sx));
	
	while(que.size()){
		P p=que.front();que.pop();
		if(p.first==gy&&p.second==gx) break;
	
		for(int i=0;i<4;i++){
			int ny=p.first+dy[i],nx=p.second+dx[i];
			if(ny>=0 && nx>=0 && ny<h && nx<w && store[ny][nx]!='#' && d[ny][nx]==INF){
				d[ny][nx]=d[p.first][p.second]+1;
				que.push(P(ny,nx));
			}
		}
	}
	
	return d[gy][gx]!=INF;
}

int main(){
	int w,h,n;
	int gx,gy;
	bool flag=false;
	P open[1100];
	cin>>w>>h;
	
	/*for(int i=0;i<1100;i++){
		for(int j=0;j<1100;j++){
			store[i][j]='#';
		}
	}*/
	
	for(int i=0;i<1100;i++){
		for(int j=0;j<1100;j++){
			d[i][j]=INF;
		}
	}

	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			cin>>store[i][j];
			if(store[i][j]=='t'){
				gx=j;gy=i;
			}
		}
	}
	
	cin>>n;
	for(int i=1;i<=n;i++){
		int x,y;
		cin>>x>>y;
		open[i]=P(y,x);
	}
	
	for(int i=0;i<=n;i++){
		if(i>0){
			store[open[i].first][open[i].second]='.';
			for(int j=0;j<4;j++){
				int ny=open[i]+dy[j],nx=open[i].second+dx[j]
				if(ny=>0 && nx>=0 && ny<h && nx<w && d[ny][nx]!=INF) flag=true;
			}
		}
		if((i==0 && bfs(w,h,0,0,gy,gx)) || (i>0 && flag && bfs(w,h,open[i].first,open[i].second,gy,gx))) {
			cout<<i<<endl;
			return 0;
		}
		flag=false;
	}
	cout<<-1<<endl;
	return 0;
}

			

Compiler output:
a.cc: In function 'int main()':
a.cc:73:47: error: no match for 'operator+' (operand types are 'P' {aka 'std::pair<int, int>'} and 'int')
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                        ~~~~~~~^~~~~~
      |                                              |     |
      |                                              |     int
      |                                              P {aka std::pair<int, int>}
In file included from /usr/include/c++/14/string:48,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_iterator.h:627:5: note: candidate: 'template<class _Iterator> constexpr std::reverse_iterator<_Iterator> std::operator+(typename reverse_iterator<_Iterator>::difference_type, const reverse_iterator<_Iterator>&)'
  627 |     operator+(typename reverse_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:627:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note: candidate: 'template<class _Iterator> constexpr std::move_iterator<_IteratorL> std::operator+(typename move_iterator<_IteratorL>::difference_type, const move_iterator<_IteratorL>&)'
 1798 |     operator+(typename move_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
In file included from /usr/include/c++/14/string:54:
/usr/include/c++/14/bits/basic_string.h:3598:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3598 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3598:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   'P' {aka 'std::pair<int, int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3616:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3616 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   mismatched types 'const _CharT*' and 'std::pair<int, int>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3635:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3635 |     operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'int'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3652:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3652 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   'P' {aka 'std::pair<int, int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3670:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 3670 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   'P' {aka 'std::pair<int, int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3682:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3682 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   'P' {aka 'std::pair<int, int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3689:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3689 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   'P' {aka 'std::pair<int, int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3696:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3696 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   'P' {aka 'std::pair<int, int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3719:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3719 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   mismatched types 'const _CharT*' and 'std::pair<int, int>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3726:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3726 |     operator+(_CharT __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'int'
   73 |                                 int ny=open[i]+dy[j],nx=open[i].second+dx[j]
      |                                                    ^
/usr/include/c++/14/bits/basic_string.h:3733:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const _CharT*)'
 3733 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3733:5: note:   template argument deduction/substitution failed:
a.cc:73:52: note:   'P' {aka 'std::pair<int, int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   73 |                                 int ny=open[i]+dy[j],nx=open[i]