Language: C++

#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define fo(a,b) for(int a=0;a<b;a++)
#define Sort(a) sort(a.begin(),a.end())
#define rev(a) reverse(a.begin(),a.end())
#define fi first
#define se second
 int wari(int a,int b) {
   if(a%b==0)
     return a/b;
   else
     return a/b+1;
 }
 int keta(int a){
  double b=a;
  b=log10(b);
  int c=b;
  return c+1;
 }
 int souwa(int a){
  return a*(a+1)/2;
 }
 int lcm(int a,int b){
  int d=a,e=b,f;
  if(a<b)
    swap(a,b);
  int c,m=1;
  while(m){
    c=a%b;
    if(c==0){
       f=b;
      m--;
    }
    else{
      a=b;
      b=c;
 }
  }
  return d*e/f;
    }
  int gcm(int a,int b){
      int d=a,e=b,f;
  if(a<b)
    swap(a,b);
  int c,m=1;
  while(m){
    c=a%b;
    if(c==0){
       f=b;
      m--;
    }
    else{
      a=b;
      b=c;
 }
  }
  return f;
  }
 bool prime(int a){
   if(a<2)
     return false;
   else if(a==2)
     return true;
   else if(a%2==0)
     return false;
   double b=sqrt(a);
    for(int i=3;i<=b;i+=2){
      if(a%i==0){
        return false;
      }
    }
   return true;
 }
signed main(){
  int a,b,e,f;
  cin>>a>>b;
  vector<pair<int,int>> c(b),d(a,(1,0));
  fo(i,a){
    cin>>c[i].fi>>c[i].se;
    c[i].fi--;
    c[i].se--;
  }
  d[0].se=1;
  fo(i,b){
    e=c[i].fi;
    f=c[i].se;
    if(d[e].se==1){
      d[f].fi++;
      d[f].se=1;
      d[e].fi--;
      if(d[e].fi==0)
        d[e].se=0;
    }
    else{
      d[e].fi--;
      d[f].fi++;
    }
  }
  int g=0;
  fo(i,a){
    if(d[i].se==1)
      g++;
  }
  cout<<g<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:78:39: error: no matching function for call to 'std::vector<std::pair<int, int> >::vector(int&, int)'
   78 |   vector<pair<int,int>> c(b),d(a,(1,0));
      |                                       ^
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_vector.h:707:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&) [with <template-parameter-2-2> = _InputIterator; _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  707 |         vector(_InputIterator __first, _InputIterator __last,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:707:9: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/14/bits/stl_algobase.h:65,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_iterator_base_types.h: In substitution of 'template<class _InIter> using std::_RequireInputIter = std::__enable_if_t<((bool)std::is_convertible<typename std::iterator_traits< <template-parameter-1-1> >::iterator_category, std::input_iterator_tag>::value)> [with _InIter = int]':
/usr/include/c++/14/bits/stl_vector.h:705:9:   required from here
  705 |                typename = std::_RequireInputIter<_InputIterator>>
      |                ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator_base_types.h:252:57: error: no type named 'iterator_category' in 'struct std::iterator_traits<int>'
  252 |                                    input_iterator_tag>::value>;
      |                                                         ^~~~~
/usr/include/c++/14/bits/stl_vector.h:678:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::initializer_list<_Tp>, const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >]'
  678 |       vector(initializer_list<value_type> __l,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:678:43: note:   no known conversion for argument 1 from 'int' to 'std::initializer_list<std::pair<int, int> >'
  678 |       vector(initializer_list<value_type> __l,
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:659:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, std::__type_identity_t<_Alloc>&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; std::__type_identity_t<_Alloc> = std::allocator<std::pair<int, int> >]'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:659:23: note:   no known conversion for argument 1 from 'int' to 'std::vector<std::pair<int, int> >&&'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |              ~~~~~~~~~^~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::false_type) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >; std::false_type = std::false_type]'
  640 |       vector(vector&& __rv, const allocator_type& __m, false_type)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:635:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::true_type) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >; std::true_type = std::true_type]'
  635 |       vector(vector&& __rv, const allocator_type& __m, true_type) noexcept
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:635:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:624:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&, std::__type_identity_t<_Alloc>&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; std::__type_identity_t<_Alloc> = std::allocator<std::pair<int, int> >]'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:624:28: note:   no known conversion for argument 1 from 'int' to 'const std::vector<std::pair<int, int> >&'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |              ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  620 |       vector(vector&&) noexcept = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:601:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  601 |       vector(const vector& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:601:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:569:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const value_type&, const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; size_type = long unsigned int; value_type = std::pair<int, int>; allocator_type = std::allocator<std::pair<int, int> >]'
  569 |       vector(size_type __n, const value_type& __value,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:569:47: note:   no known conversion for argument 2 from 'int' to 'const std::vector<std::pair<int, int> >::value_type&' {aka 'const std::pair<int, int>&'}
  569 |       vector(size_type __n, const value_type& __value,
      |                             ~~~~~~~~~~~~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; size_type = long unsigned int; allocator_type = std::allocator<std::pair<int, int> >]'
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:51: note:   no known conversion for argument 2 from 'int' to 'const std::vector<std::pair<int, int> >::allocator_type&' {aka 'const std::allocator<std::pair<int, int> >&'}
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |                             ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const allocator_type&) [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >; allocator_type = std::allocator<std::pair<int, int> >]'
  542 |       vector(const allocator_type& __a) _GLIBCXX_NOEXCEPT
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:531:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector() [with _Tp = std::pair<int, int>; _Alloc = std::allocator<std::pair<int, int> >]'
  531 |       vector() = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:531:7: note:   candidate expects 0 arguments, 2 provided