Language: C++

#include<bits/stdc++.h>
#include<unordered_set>
#include<unordered_map>
#include <algorithm> 
#include <iostream>
#include <string>
#include <cmath>
using namespace std;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define FOR(i,a,b) for(ll i=(a);i<(b);i++)
#define FORR(i,a,b)for(ll i=(a);i<=(b);i++)
#define repR(i,n) for(ll i=n;i>=0;i--)
#define all(v)(v).begin(),(v).end()
#define rall(v)(v).rbegin(),(v).rend()
#define F first
#define S second
#define pb push_back
#define pu push
#define COUT(x) cout<<(x)<<endl
#define PQ priority_queue<ll>
#define PQR priority_queue<ll,vector<ll>,greater<ll>>
#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define mp make_pair
#define maxs(x,y) (x = max(x,y))
#define mins(x,y) (x = min(x,y))
#define sz(x) (int)(x).size()
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll MOD = 1000000007LL;
const ll INF = 1LL << 60;
using vll = vector<ll>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvll = vector<vll>;
using vstr = vector<string>;
using pll = pair<ll, ll>;
using vc = vector<char>;
using vvc = vector<vc>;
ll dx[4]={0,1,0,-1};
ll dy[4]={1,0,-1,0};
int main(){
   
    string s;
    cin >> s;
 
    vll cnt(26, 0);
    vll n = s.size();
    rep (i, n)
    {
        ++cnt[s[i] - 'a'];
    }
 
    ll ans = 0;
    rep (i, 26)
    {
        ans += cnt[i] * (cnt[i] - 1) / 2;
    }
 
    cout << n * (n - 1) / 2 + 1 - ans << "\n";
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:49:19: error: conversion from 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} to non-scalar type 'vll' {aka 'std::vector<long long int>'} requested
   49 |     vll n = s.size();
      |             ~~~~~~^~
a.cc:10:36: error: no match for 'operator<' (operand types are 'long long int' and 'vll' {aka 'std::vector<long long int>'})
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                    ^ ~~~
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
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:10:40: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   mismatched types 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   'vll' {aka 'std::vector<long long int>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   'vll' {aka 'std::vector<long long int>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
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:10:40: note:   mismatched types 'const std::pair<_T1, _T2>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
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:10:40: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/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:10:40: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
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:10:40: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'long long int'
   10 | #define rep(i, n) for (ll i = 0; i < (n); i++)
      |                                        ^
a.cc:50:5: note: in expansion of macro 'rep'
   50 |     rep (i, n)
      |     ^~~
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_Ch