Language: C++

//  LINK ZADATKA:http://abc070.contest.atcoder.jp/tasks/abc070_b
 
#include <queue>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <complex>
#include <fstream>
#include <cstring>
#include <string>
#include <climits>

using namespace std;

typedef long long ll;
typedef complex<double> point;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector< vector<int> > vvi;


#define FOR(k,a,b) for(int k=(a); k<=(b); ++k)
#define REP(k,a) for(int k=0; k<(a);++k)
#define SZ(a) int((a).size())
#define ALL(c) (c).begin(),(c).end()
#define PB push_back
#define MP make_pair
#define INF 999999999
#define INFLONG 1000000000000000000
#define MOD 1000000007
#define MAX 100
#define ITERS 100
#define MAXM 200000
#define MAXN 1000000
#define _gcd __gcd
#define eps 1e-9
int polje[110], start, end;
int main(){
	int a, b, c, d;

	scanf("%d %d %d %d", &a, &b, &c, &d);
	
	FOR(i, a, b) polje[i]++;
	FOR(i, c, d) polje[i]++;
	FOR(i, 0, 100){
		//printf("%d ", polje[i]);
		if(polje[i] == 2 && !start){
			start = i;
		}
		if(polje[i] != 2 && start && !end){
			end = i-1;
		}
	}
	//printf("%d %d\n", start, end);
	printf("%d\n", end-start);
}

Compiler output:
a.cc: In function 'int main()':
a.cc:65:47: error: reference to 'end' is ambiguous
   65 |                 if(polje[i] != 2 && start && !end){
      |                                               ^~~
In file included from /usr/include/c++/14/deque:68,
                 from /usr/include/c++/14/queue:62,
                 from a.cc:3:
/usr/include/c++/14/bits/range_access.h:116:37: note: candidates are: 'template<class _Tp> const _Tp* std::end(const valarray<_Tp>&)'
  116 |   template<typename _Tp> const _Tp* end(const valarray<_Tp>&) noexcept;
      |                                     ^~~
/usr/include/c++/14/bits/range_access.h:115:31: note:                 'template<class _Tp> _Tp* std::end(valarray<_Tp>&)'
  115 |   template<typename _Tp> _Tp* end(valarray<_Tp>&) noexcept;
      |                               ^~~
/usr/include/c++/14/bits/range_access.h:106:5: note:                 'template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::end(_Tp (&)[_Nm])'
  106 |     end(_Tp (&__arr)[_Nm]) noexcept
      |     ^~~
/usr/include/c++/14/bits/range_access.h:85:5: note:                 'template<class _Container> constexpr decltype (__cont.end()) std::end(const _Container&)'
   85 |     end(const _Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/bits/range_access.h:74:5: note:                 'template<class _Container> constexpr decltype (__cont.end()) std::end(_Container&)'
   74 |     end(_Container& __cont) -> decltype(__cont.end())
      |     ^~~
In file included from /usr/include/c++/14/bits/stl_deque.h:63,
                 from /usr/include/c++/14/deque:66:
/usr/include/c++/14/initializer_list:99:5: note:                 'template<class _Tp> constexpr const _Tp* std::end(initializer_list<_Tp>)'
   99 |     end(initializer_list<_Tp> __ils) noexcept
      |     ^~~
a.cc:52:24: note:                 'int end'
   52 | int polje[110], start, end;
      |                        ^~~
a.cc:66:25: error: reference to 'end' is ambiguous
   66 |                         end = i-1;
      |                         ^~~
/usr/include/c++/14/bits/range_access.h:116:37: note: candidates are: 'template<class _Tp> const _Tp* std::end(const valarray<_Tp>&)'
  116 |   template<typename _Tp> const _Tp* end(const valarray<_Tp>&) noexcept;
      |                                     ^~~
/usr/include/c++/14/bits/range_access.h:115:31: note:                 'template<class _Tp> _Tp* std::end(valarray<_Tp>&)'
  115 |   template<typename _Tp> _Tp* end(valarray<_Tp>&) noexcept;
      |                               ^~~
/usr/include/c++/14/bits/range_access.h:106:5: note:                 'template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::end(_Tp (&)[_Nm])'
  106 |     end(_Tp (&__arr)[_Nm]) noexcept
      |     ^~~
/usr/include/c++/14/bits/range_access.h:85:5: note:                 'template<class _Container> constexpr decltype (__cont.end()) std::end(const _Container&)'
   85 |     end(const _Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/bits/range_access.h:74:5: note:                 'template<class _Container> constexpr decltype (__cont.end()) std::end(_Container&)'
   74 |     end(_Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/initializer_list:99:5: note:                 'template<class _Tp> constexpr const _Tp* std::end(initializer_list<_Tp>)'
   99 |     end(initializer_list<_Tp> __ils) noexcept
      |     ^~~
a.cc:52:24: note:                 'int end'
   52 | int polje[110], start, end;
      |                        ^~~
a.cc:70:24: error: reference to 'end' is ambiguous
   70 |         printf("%d\n", end-start);
      |                        ^~~
/usr/include/c++/14/bits/range_access.h:116:37: note: candidates are: 'template<class _Tp> const _Tp* std::end(const valarray<_Tp>&)'
  116 |   template<typename _Tp> const _Tp* end(const valarray<_Tp>&) noexcept;
      |                                     ^~~
/usr/include/c++/14/bits/range_access.h:115:31: note:                 'template<class _Tp> _Tp* std::end(valarray<_Tp>&)'
  115 |   template<typename _Tp> _Tp* end(valarray<_Tp>&) noexcept;
      |                               ^~~
/usr/include/c++/14/bits/range_access.h:106:5: note:                 'template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::end(_Tp (&)[_Nm])'
  106 |     end(_Tp (&__arr)[_Nm]) noexcept
      |     ^~~
/usr/include/c++/14/bits/range_access.h:85:5: note:                 'template<class _Container> constexpr decltype (__cont.end()) std::end(const _Container&)'
   85 |     end(const _Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/bits/range_access.h:74:5: note:                 'template<class _Container> constexpr decltype (__cont.end()) std::end(_Container&)'
   74 |     end(_Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/initializer_list:99:5: note:                 'template<class _Tp> constexpr const _Tp* std::end(initializer_list<_Tp>)'
   99 |     end(initializer_list<_Tp> __ils) noexcept
      |     ^~~
a.cc:52:24: note:                 'int end'
   52 | int polje[110], start, end;
      |                        ^~~