Language: C++

#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp> //required
//#include <ext/pb_ds/tree_policy.hpp> 
#define ll long long
#define lb long double
#define pb push_back
#define loop(i,start,n) for(ll i=start;i<n;i++)
#define rloop(i,n,start)for(ll i=n;i>=start;i--)
#define mod 1000000007
#define endl "\n"
#define INF     1e15
#define NEG_INF -1e15
#define pll pair<ll,ll>
#define x first
#define y second
#define all(x) x.begin(),x.end()
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
 
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
//template <typename T> using ordered_set =  tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; 
//using namespace __gnu_pbds;

int main(){
	IOS;
	string str;
	cin >> str;
	ll cnt = 0;
	str = ' ' + str;
	ll dp[4] = {0};
	loop(i, 1, str){
		if(s[i] == 'R')
			dp[i] = dp[i - 1] + 1;
		else
			dp[i] = 0;
		cnt = max(cnt, dp[i]);
	}
	cout << cnt << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:41: error: no match for 'operator<' (operand types are 'long long int' and 'std::string' {aka 'std::__cxx11::basic_string<char>'})
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                         ^
a.cc:55:9: note: in expansion of macro 'loop'
   55 |         loop(i, 1, str){
      |         ^~~~
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:1:
/usr/include/c++/14/bits/regex.h:1143:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1143 |     operator<(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1143:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/regex.h:1224:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1224 |     operator<(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1224:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/regex.h:1317:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1317 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1317:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/regex.h:1391:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1391 |     operator<(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1391:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/regex.h:1485:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1485 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1485:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/regex.h:1560:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1560 |     operator<(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1560:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/regex.h:1660:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1660 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1660:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 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_pair.h:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::pair<_T1, _T2>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i=start;i<n;i++)
      |                                          ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:55:20: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'long long int'
   55 |         loop(i, 1, str){
      |                    ^~~
a.cc:7:42: note: in definition of macro 'loop'
    7 | #define loop(i,start,n) for(ll i