Language: C++

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
#define lli long long int
#define fop(i,m,n) for (int i=(m);i<(n);i++)
#define FOP(i,m,n) for (int i=(m)-1;i>=(n);--i)
#define test(x) cout << #x << ' ' << x << endl;
#define printv(a) {\
    for (auto i : a) cout << i << ' ';\
    cout << '\n';\
}
#define eb emplace_back
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define pii pair<int,int>
#define pdd pair<ld,ld>
#define ld long double
#define pll pair<lli,lli>
#define tiii tuple<int,int,int>
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define X first
#define Y second
#define oset tree<lli,null_type,less<lli>,rb_tree_tag,tree_order_statistics_node_update>
auto SEED = chrono::steady_clock::now().time_since_epoch().count();
mt19937 rng(SEED);

// AC automaton will help me get AC!
struct AC {
    vector <vector <int>> ch;
    vector <int> cnt, f;
    AC () {extend();}
    void extend() {
        ch.pb(vector <int>(26, 0));
        cnt.pb(0);
    }
    int next(int u, int v) {
        if (!ch[u][v]) {
            ch[u][v] = ch.size();
            extend();
        }
        return ch[u][v];
    }
    void insert(string &s) {
        int now = 0;
        for (char c : s) {
            now = next(now, c - 'a');
        }
        cnt[now]++;
    }
    void build_fail() {
        f.assign(ch.size(), 0);
        queue <int> q;
        for (int i = 0; i < 26; ++i) if (ch[0][i]) q.push(ch[0][i]);
        while (q.size()) {
            int v = q.front(); q.pop();
            for (int i = 0; i < 26; ++i) if (ch[v][i]) {
                    int k = f[v];
                    while (k && !ch[k][i]) k = f[k];
                    if (ch[k][i]) k = ch[k][i];
                    f[ch[v][i]] = k;
                    cnt[ch[v][i]] += cnt[k];
                    q.push(ch[v][i]);
                }
        }
    }
    int match(string &s) {
        int k = 0, ans = 0;
        for (char c : s) {
            while (k && !ch[k][c - 'a']) k = f[k];
            if (ch[k][c - 'a']) k = ch[k][c - 'a'];
            ans += cnt[k];
        }
        return ans;
    }
};

const int mod = 1e9 + 7, x = 864197532, N = 2000087, logN = 17;

int main () {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    int a[n];
    fop (i,0,n) cin >> a[i];
    sort(a, a + n);
    lli ans = 0;
    fop (i,0,n) fop (j,i + 1,n) {
        ans += max((lower_bound(a, a + n, a[i] + a[j]) - a) - 1 - j, 0ll);
    }
    cout << ans << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:92:19: error: no matching function for call to 'max(long int, long long int)'
   92 |         ans += max((lower_bound(a, a + n, a[i] + a[j]) - a) - 1 - j, 0ll);
      |                ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:92:19: note:   deduced conflicting types for parameter 'const _Tp' ('long int' and 'long long int')
   92 |         ans += max((lower_bound(a, a + n, a[i] + a[j]) - a) - 1 - j, 0ll);
      |                ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:92:19: note:   mismatched types 'std::initializer_list<_Tp>' and 'long int'
   92 |         ans += max((lower_bound(a, a + n, a[i] + a[j]) - a) - 1 - j, 0ll);
      |                ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~