Language: C++

#include"bits/stdc++.h"

#define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
#define RFOR(i,a,b) for (ll i=(b)-1,__last_##i=(a);i>=__last_##i;i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define __GET_MACRO3(_1, _2, _3, NAME, ...) NAME
#define rep(...) __GET_MACRO3(__VA_ARGS__, FOR, REP)(__VA_ARGS__)
#define rrep(...) __GET_MACRO3(__VA_ARGS__, RFOR, RREP)(__VA_ARGS__)
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
	REP(i, v.size()) { if (i)os << " "; os << v[i]; }return os;
}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
	REP(i, v.size()) { if (i)os << endl; os << v[i]; }return os;
}


void solve();

int main() {

	solve();
	return 0;

}

void solve() {

	ll m, n_min, n_max;
	vector<ll> s;



	cin >> m >> n_min >> n_max;

	while (m > 0) {
		ll gap = 0, ans = 0;
		s.resize(m);
		REP(i, m) {

			cin >> s[i];

		}

		FOR(i, n_min-1, n_max ) {

			if (s[i] - s[i + 1] >= gap) {

				ans = i+1;
				gap = s[i] - s[i + 1];

			}

		}

		cout << ans << endl;

	}

}

Compiler output:
a.cc:10:22: error: 'ostream' does not name a type
   10 | template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
      |                      ^~~~~~~
a.cc:13:22: error: 'ostream' does not name a type
   13 | template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
      |                      ^~~~~~~
a.cc: In function 'void solve()':
a.cc:29:9: error: 'll' was not declared in this scope
   29 |         ll m, n_min, n_max;
      |         ^~
a.cc:30:9: error: 'vector' was not declared in this scope
   30 |         vector<ll> s;
      |         ^~~~~~
a.cc:30:9: note: suggested alternatives:
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:428:11: note:   'std::vector'
  428 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
/usr/include/c++/14/vector:93:13: note:   'std::pmr::vector'
   93 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
a.cc:30:20: error: 's' was not declared in this scope
   30 |         vector<ll> s;
      |                    ^
a.cc:34:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
   34 |         cin >> m >> n_min >> n_max;
      |         ^~~
      |         std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~
a.cc:34:16: error: 'm' was not declared in this scope; did you mean 'tm'?
   34 |         cin >> m >> n_min >> n_max;
      |                ^
      |                tm
a.cc:34:21: error: 'n_min' was not declared in this scope
   34 |         cin >> m >> n_min >> n_max;
      |                     ^~~~~
a.cc:34:30: error: 'n_max' was not declared in this scope
   34 |         cin >> m >> n_min >> n_max;
      |                              ^~~~~
a.cc:37:19: error: expected ';' before 'gap'
   37 |                 ll gap = 0, ans = 0;
      |                   ^~~~
      |                   ;
a.cc:39:21: error: expected ';' before 'i'
   39 |                 REP(i, m) {
      |                     ^
a.cc:3:28: note: in definition of macro 'FOR'
    3 | #define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
      |                            ^
a.cc:39:17: note: in expansion of macro 'REP'
   39 |                 REP(i, m) {
      |                 ^~~
a.cc:39:21: error: 'i' was not declared in this scope
   39 |                 REP(i, m) {
      |                     ^
a.cc:3:49: note: in definition of macro 'FOR'
    3 | #define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
      |                                                 ^
a.cc:39:17: note: in expansion of macro 'REP'
   39 |                 REP(i, m) {
      |                 ^~~
a.cc:3:51: error: '__last_i' was not declared in this scope
    3 | #define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
      |                                                   ^~~~~~~
a.cc:5:18: note: in expansion of macro 'FOR'
    5 | #define REP(i,n) FOR(i,0,n)
      |                  ^~~
a.cc:39:17: note: in expansion of macro 'REP'
   39 |                 REP(i, m) {
      |                 ^~~
a.cc:45:21: error: expected ';' before 'i'
   45 |                 FOR(i, n_min-1, n_max ) {
      |                     ^
a.cc:3:28: note: in definition of macro 'FOR'
    3 | #define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
      |                            ^
a.cc:45:21: error: 'i' was not declared in this scope
   45 |                 FOR(i, n_min-1, n_max ) {
      |                     ^
a.cc:3:49: note: in definition of macro 'FOR'
    3 | #define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
      |                                                 ^
a.cc:3:51: error: '__last_i' was not declared in this scope
    3 | #define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
      |                                                   ^~~~~~~
a.cc:45:17: note: in expansion of macro 'FOR'
   45 |                 FOR(i, n_min-1, n_max ) {
      |                 ^~~
a.cc:47:48: error: 'gap' was not declared in this scope
   47 |                         if (s[i] - s[i + 1] >= gap) {
      |                                                ^~~
a.cc:49:33: error: 'ans' was not declared in this scope; did you mean 'abs'?
   49 |                                 ans = i+1;
      |                                 ^~~
      |                                 abs
a.cc:56:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   56 |                 cout << ans << endl;
      |                 ^~~~
      |                 std::cout
/usr/include/c++/14/iostream:63:18: note: 'std::cout' declared here
   63 |   extern ostream cout;          ///< Linked to standard output
      |                  ^~~~
a.cc:56:25: error: 'ans' was not declared in this scope; did you mean 'abs'?
   56 |                 cout << ans << endl;
      |                         ^~~
      |                         abs
a.cc:56:32: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   56 |                 cout << ans << endl;
      |                                ^~~~
      |                                std::endl
In file included from /usr/include/c++/14/istream:41,
                 from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~