Language: C++

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<string>
#include<sstream>
#include<iomanip>
#include<utility>
#include<cmath>
#include<set>
#include<list>
#include<queue>
#include<stack>
#include<deque>
#include<map>
#include<set>
#include<cstring>
#include<iterator>
#include<bitset>
#include<assert.h>
using namespace std;
 
struct edge {int /*from,*/to,cost;};
typedef long long ll;
typedef pair<int,int> P;
typedef pair<int,pair<int,int> > PP;
typedef vector<int> VI;
typedef vector<long long int> VL;
typedef vector<edge> VE;
static const int MOD = 1000000007;
static const int INF = 2147483647;
//static const long long INF = 9223372000000000000;
//static const long long INF = 9223372000000000000/2;
//static const int INF = 1000010000;
//int dx4[4] = {0,1,0,-1}, dy4[4] = {-1,0,1,0};
//int dx5[5] = {-1,0,0,0,1}, dy5[5] = {0,-1,0,1,0};
//int dx8[8] = {-1,0,1,1,1,0,-1,-1}, dy8[8] = {1,1,1,0,-1,-1,-1,0};
//int dx9[9] = {-1,0,1,1,1,0,-1,-1,0}, dy9[9] = {1,1,1,0,-1,-1,-1,0,0};
#define PB push_back
#define MP make_pair
#define FI first
#define SE second
#define NP next_permutation
#define PQ priority_queue
#define UB upper_bound
#define LB lower_bound
#define ALL(x) (x).begin(),(x).end()
#define SZ(a) int((a).size())
#define LEN(a) int((a).length())
#define MAX(a,b,c) max((a),max((b),(c)))
#define MIN(a,b,c) min((a),min((b),(c)))
#define SORT(c) sort((c).begin(),(c).end())
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,x) for(int i=0;i<(int)(x);i++)
#define REP1(i,x) for(int i=1;i<=(int)(x);i++)
#define RREP(i,x) for(int i=((int)(x)-1);i>=0;i--)
#define RREP1(i,x) for(int i=((int)(x));i>0;i--)
//#define int ll

signed main(){
    string s;
    cin >> s;
    REP(i,4) cout >> s[i];
    printf(" ");
    FOR(i,4,12) cout >> s[i];
    puts(" ");
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:64:19: error: no match for 'operator>>' (operand types are 'std::ostream' {aka 'std::basic_ostream<char>'} and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'})
   64 |     REP(i,4) cout >> s[i];
a.cc:64:19: note: candidate: 'operator>>(int, int)' (built-in)
a.cc:64:19: note:   no known conversion for argument 1 from 'std::ostream' {aka 'std::basic_ostream<char>'} to 'int'
In file included from /usr/include/c++/14/string:55,
                 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/basic_string.tcc:835:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
  835 |     operator>>(basic_istream<_CharT, _Traits>& __in,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.tcc:835:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
In file included from /usr/include/c++/14/bits/memory_resource.h:38,
                 from /usr/include/c++/14/string:68:
/usr/include/c++/14/cstddef:131:5: note: candidate: 'template<class _IntegerType> constexpr std::__byte_op_t<_IntegerType> std::operator>>(byte, _IntegerType)'
  131 |     operator>>(byte __b, _IntegerType __shift) noexcept
      |     ^~~~~~~~
/usr/include/c++/14/cstddef:131:5: note:   template argument deduction/substitution failed:
a.cc:64:14: note:   cannot convert 'std::cout' (type 'std::ostream' {aka 'std::basic_ostream<char>'}) to type 'std::byte'
   64 |     REP(i,4) cout >> s[i];
      |              ^~~~
In file included from /usr/include/c++/14/istream:1109,
                 from /usr/include/c++/14/iostream:42:
/usr/include/c++/14/bits/istream.tcc:978:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT&)'
  978 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
      |     ^~~~~~~~
/usr/include/c++/14/bits/istream.tcc:978:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/istream:849:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char&)'
  849 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:849:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/istream:854:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char&)'
  854 |     operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
      |     ^~~~~~~~
/usr/include/c++/14/istream:854:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/istream:896:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _CharT*)'
  896 |     operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:896:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/istream:939:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, unsigned char*)'
  939 |     operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:939:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/istream:945:5: note: candidate: 'template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(basic_istream<char, _Traits>&, signed char*)'
  945 |     operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
      |     ^~~~~~~~
/usr/include/c++/14/istream:945:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<char, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/istream:1099:5: note: candidate: 'template<class _Istream, class _Tp> _Istream&& std::operator>>(_Istream&&, _Tp&&)'
 1099 |     operator>>(_Istream&& __is, _Tp&& __x)
      |     ^~~~~~~~
/usr/include/c++/14/istream:1099:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/istream: In substitution of 'template<class _Istream, class _Tp> _Istream&& std::operator>>(_Istream&&, _Tp&&) [with _Istream = std::basic_ostream<char>&; _Tp = char&]':
a.cc:64:25:   required from here
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/istream:1099:5: error: no type named 'type' in 'struct std::enable_if<false, void>'
 1099 |     operator>>(_Istream&& __is, _Tp&& __x)
      |     ^~~~~~~~
In file included from a.cc:8:
/usr/include/c++/14/iomanip:76:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Resetiosflags)'
   76 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Resetiosflags __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:76:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/iomanip:106:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setiosflags)'
  106 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setiosflags __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:106:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/iomanip:137:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setbase)'
  137 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setbase __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:137:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/iomanip:177:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setfill<_CharT>)'
  177 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setfill<_CharT> __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:177:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/iomanip:207:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setprecision)'
  207 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setprecision __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:207:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/iomanip:237:5: note: candidate: 'template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Setw)'
  237 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Setw __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:237:5: note:   template argument deduction/substitution failed:
a.cc:64:25: note:   'std::ostream' {aka 'std::basic_ostream<char>'} is not derived from 'std::basic_istream<_CharT, _Traits>'
   64 |     REP(i,4) cout >> s[i];
      |                         ^
/usr/include/c++/14/iomanip:271:5: note: candidate: 'template<class _CharT, class _Traits, class _MoneyT> std::basic_istream<_CharT, _Traits>& std::operator>>(basic_istream<_CharT, _Traits>&, _Get_money<_MoneyT>)'
  271 |     operator>>(basic_istream<_CharT, _Traits>& __is, _Get_money<_MoneyT> __f)
      |     ^~~~~~~~
/usr/include/c++/14/iomanip:271:5: note:   template