#include <bits/stdc++.h>
using namespace std;
#define int long long
// #define int __int128
using ll = long long;
typedef unsigned long long ull;
using ld = long double;
inline int read();
inline void write(int);
#define inf 0x3f3f3f3f         // 1061109567
#define INF 0x3f3f3f3f3f3f3f3f // 4557430888798830399
#define lowbit(x) ((x) & (-x))
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x).size()
#define pb push_back
// #define mp make_pair
#define PII pair<long, long>
#define fi first
#define se second
#define mem(x, y) memset(x, y, sizeof(x))
#define endl '\n'
const double PI = acos(-1.0);
#define eps 1e-7
#define rep(i, a, b) for (int i = a; i <= b; i++)
#define per(i, a, b) for (int i = a; i >= b; i--)
#define debug(x) cerr << #x << ": " << x << endl;
const int d[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
const int maxn = 1e6 + 5;
const int mod = 998244353;
const int N = 1011;
int n;
int fa[maxn];
int rt(int x)
{
    while (x != fa[x])
        x = fa[x] = fa[fa[x]];
    return x;
}
bool merge(int u, int v)
{
    u = rt(u);
    v = rt(v);
    if (u == v)
        return false;
    fa[v] = u;
    return true;
}
void solve()
{
    cin >> n;
    for (int i = 1; i <= n + 1; ++i)
        fa[i] = i;
    int ans = 1;
    for (int i = 1; i <= n; ++i)
    {
        int l, r;
        cin >> l >> r;
        if (!merge(l, r + 1))
            ans = 0;
    }
    cout << ans << endl;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    // cout << fixed;
    // cout.precision(18);
    int T = 1;
    // cin >> T;
    while (T--)
        solve();
    return 0;
}

inline int read()
{
    int x = 0, f = 1;
    char ch = getchar();
    while (!isdigit(ch))
    {
        if (ch == '-')
            f = -1;
        ch = getchar();
    }
    while (isdigit(ch))
    {
        x = (x << 1) + (x << 3) + (ch ^ '0');
        ch = getchar();
    }
    return x * f;
}

inline void write(int x)
{
    if (x < 0)
        putchar('-'), x = -x;
    if (x > 9)
        write(x / 10);
    putchar(x % 10 + '0');
    return;
}