Language: C++

#define debug_interval ','
#define dump_interval ' '
#define debug_toggle 1
//{
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define INT_MAX LLONG_MAX
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define fi first
#define se second
#define mp make_pair
#define rev reverse
#define dans dump(ans)
#define MOD 1000000007
#define amp(v,n) (v).count(n)?v[n]++:v[n]=1;

//{
inline int toInt(string s){int v;istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x){ostringstream sout;sout<<x;return sout.str();}
template<class...A> inline void dump(){cout<<endl;}
template<class...A> inline void dump_rest() {cout<<endl;}
template<class T, class...A> inline void dump_rest(const T& first, const A&... rest){cout<<dump_interval<<first;dump_rest(rest...);}
template<class T,class...A> inline void dump(const T&first,const A&...rest){cout<<first;dump_rest(rest...);}
template<class...A> inline void debug(){cerr<<endl;}
template<class...A> inline void debug_rest() {cerr<<endl;}
template<class T, class...A> inline void debug_rest(const T& first, const A&... rest){cerr<<debug_interval<<first;debug_rest(rest...);}
template<class T,class...A> inline void debug(const T&first,const A&...rest){if(debug_toggle)cerr<<first,debug_rest(rest...);}
//}

typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;

template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}
template<int m>class mint{private:int i;public:mint() : i(0){}mint(int i): i((i%m+m)%m){}mint operator+(const mint& o){return o.i+i;}mint operator*(const mint& o){return o.i*i;}mint operator-(){return -i;}operator int() {return i;}};

string s;
int aa[26];
bool a=1;

main(){
	cin>>s;
	rep(i,s.size())aa[(int)(s[i]-'a')]++;
	rep(i,26){
		if(aa[i]>1){
			cout<<-1<<endl;
			return 0;
		}
	}
	if(s.size()==26){
		if(s=="zyxwvutsrqponmlkjihgfedcba")cout<<-1<<endl;
		else{
			string t=s,ans;
			next_permutation(s.begin(),s.end());
			rep(i,n){
				ans+=s[i];
				if(t[i]!=s[i])break;
			}
			cout<<ans<<endl;
		}
	}
	else rep(i,26){
		if(aa[i]==0){
			cout<<s;
			cout<<(char)(i+'a')<<endl;
			return 0;
		}
	}
	cout<<-1<<endl;
}


Compiler output:
a.cc:8:9: warning: "INT_MAX" redefined
    8 | #define INT_MAX LLONG_MAX
      |         ^~~~~~~
In file included from /usr/include/c++/14/climits:42,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:38,
                 from a.cc:5:
/usr/lib/gcc/x86_64-linux-gnu/14/include/limits.h:120:9: note: this is the location of the previous definition
  120 | #define INT_MAX __INT_MAX__
      |         ^~~~~~~
a.cc:47:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   47 | main(){
      | ^~~~
a.cc: In function 'int main()':
a.cc:61:31: error: 'n' was not declared in this scope
   61 |                         rep(i,n){
      |                               ^
a.cc:9:33: note: in definition of macro 'rep'
    9 | #define rep(i,n) for(int i=0;i<(n);i++)
      |                                 ^