Binge watching

In file included from /usr/include/c++/13/string:43,
                 from /usr/include/c++/13/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:52,
                 from input/code.cpp:5:
/usr/include/c++/13/bits/allocator.h: In destructor 'constexpr std::_Vector_base<std::pair<int, int>, std::allocator<std::pair<int, int> > >::_Vector_impl::~_Vector_impl()':
/usr/include/c++/13/bits/allocator.h:184:7: error: inlining failed in call to 'always_inline' 'constexpr std::allocator< <template-parameter-1-1> >::~allocator() noexcept [with _Tp = std::pair<int, int>]': target specific option mismatch
  184 |       ~allocator() _GLIBCXX_NOTHROW { }
      |       ^
In file included from /usr/include/c++/13/vector:66,
                 from /usr/include/c++/13/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:53:
/usr/include/c++/13/bits/stl_vector.h:133:14: note: called from here
  133 |       struct _Vector_impl
      |...

#ifdef ONLINE_JUDGE
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#endif
#include "bits/stdc++.h"
#define fast ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define fill(arr,val) memset(arr,val,sizeof(arr))
#define FOR(i, a, b) for(__typeof(b) i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for(__typeof(a) i = a, _b = b; i >= _b; --i)
#define ALL(a) (a).begin(), (a).end()
#define YES cout << "YES\n"
#define NO cout << "NO\n"
#define ll long long
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define ii pair<int,int>
#define iii pair<int,pair<int,int>>
#define dq deque<int>
#define nend '\n'
using namespace std;

const ll inf = 1e18;
const int dx[] = {1,0,-1,0};
const int dy[] = {0,1,0,-1};
const int MOD = 1e9 + 7; 
const ll hashi = 2e9 + 11;

inline ll add(ll a, ll b) { return (a + b) % MOD; }
inline ll sub(ll a, ll b) { return ((a - b) % MOD + MOD) % MOD; }
inline ll mul(ll a, ll b) { return (a * b) % MOD; }

inline ll binpow(ll a, ll b) {
    ll res = 1;
    a %= MOD;
    while (b > 0) {
        if (b & 1) res = res * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return res;
}

inline ll modInverse(ll n) {
    return binpow(n, MOD - 2);
}

inline ll modDivide(ll a, ll b) {
    return (a % MOD * modInverse(b)) % MOD;
}

ll extended_gcd(ll a, ll b, ll& x, ll& y) {
    if (b == 0) {
        x = 1; y = 0;
        return a;
    }
    ll x1, y1;
    ll d = extended_gcd(b, a % b, x1, y1);
    x = y1;
    y = x1 - y1 * (a / b);
    return d;
}

void init_code() {
    fast;
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
}

void solve() {
    int n;
    cin >> n;

    vector<ii> a(n);

    FOR(i, 0, n - 1) {
        cin >> a[i].fi >> a[i].se;
    }

    sort(ALL(a), [](ii x, ii y) {
        return x.se < y.se;
    });

    int ans = 0;
    int last = 0;

    FOR(i, 0, n - 1) {
        if (a[i].fi >= last) {
            ans++;
            last = a[i].se;
        }
    }

    cout << ans << nend;
}

int main() {
    init_code();

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }

    #ifndef ONLINE_JUDGE
    cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " seconds.\n";
    #endif

    return 0;
}