Language: C++

#include <iostream>
#include <string>
#include <string.h>
#include <map>
#include <set>
#include <algorithm>
#include <vector>
#include <queue>
#include <stdio.h>
#include <cstdio>
#include <math.h>
#include <cmath>
#include <sstream>
#include <cassert>
#include <functional>
#include <cfloat>
#include <climits>
#include <cstring>
#include <stack>
#include <time.h>
#include <complex>
using namespace std;
#define forn(i,n) for(int i=0;i<(int)(n);i++)
int main()
{
	int cnt=1;
	int a,cnt;
	char ENG;
	string s;
	cin>>s;
	if(s.size()<26)
	{
		for(a=96;a<=122;a++)
		{
			ENG=a;
			s.push_back(ENG);
			forn(i,s.size())
			{
				for(int j=i+1;j<s.size();j++)
				{
					if(s[i]==s[j])
					{
						cnt=-1;
					}
				}
			}
			if(cnt)
			{
				cout<<s<<endl;
				break;
			}
			else s.pop_back();
		}
	}
	else{
		if(s="zyxwvutsrqponmlkjihgfedcba")
			cout<<"-1";
		else cout<<next_pomutation(s,s+s.size())
	}
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:27:15: error: redeclaration of 'int cnt'
   27 |         int a,cnt;
      |               ^~~
a.cc:26:13: note: 'int cnt' previously declared here
   26 |         int cnt=1;
      |             ^~~
a.cc:56:21: error: could not convert 's.std::__cxx11::basic_string<char>::operator=(((const char*)"zyxwvutsrqponmlkjihgfedcba"))' from 'std::__cxx11::basic_string<char>' to 'bool'
   56 |                 if(s="zyxwvutsrqponmlkjihgfedcba")
      |                    ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                     |
      |                     std::__cxx11::basic_string<char>
a.cc:58:47: error: no match for 'operator+' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'})
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                              ~^~~~~~~~~
      |                                              |       |
      |                                              |       std::__cxx11::basic_string<char>::size_type {aka long unsigned int}
      |                                              std::string {aka std::__cxx11::basic_string<char>}
In file included from /usr/include/c++/14/string:48,
                 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/stl_iterator.h:627:5: note: candidate: 'template<class _Iterator> constexpr std::reverse_iterator<_Iterator> std::operator+(typename reverse_iterator<_Iterator>::difference_type, const reverse_iterator<_Iterator>&)'
  627 |     operator+(typename reverse_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:627:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note: candidate: 'template<class _Iterator> constexpr std::move_iterator<_IteratorL> std::operator+(typename move_iterator<_IteratorL>::difference_type, const move_iterator<_IteratorL>&)'
 1798 |     operator+(typename move_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
In file included from /usr/include/c++/14/string:54:
/usr/include/c++/14/bits/basic_string.h:3598:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3598 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3598:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3616:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3616 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const _CharT*' and 'std::__cxx11::basic_string<char>'
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3635:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3635 |     operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3652:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3652 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const _CharT*' and 'long unsigned int'
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3670:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 3670 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   deduced conflicting types for parameter '_CharT' ('char' and 'long unsigned int')
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3682:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3682 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3689:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3689 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3696:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3696 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'}
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3719:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3719 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'const _CharT*' and 'std::__cxx11::basic_string<char>'
   58 |                 else cout<<next_pomutation(s,s+s.size())
      |                                                       ^
/usr/include/c++/14/bits/basic_string.h:3726:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3726 |     operator+(_CharT __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note:   template argument deduction/substitution failed:
a.cc:58:55: note:   mismatched types 'std::_