#include <bits/stdc++.h>
#define maxn 2000005
using namespace std;
inline int read() {
    int x = 0, f = 1; char c = getchar();
    while (c < '0' || c > '9') { if (c == '-') f = -1; c = getchar(); }
    while (c >= '0' && c <= '9') { x = x * 10 + c - '0'; c = getchar(); }
    return x * f;
}

int n, m, k;

struct edge {
    int v, w, nxt;
}e[maxn * 5];
int head[maxn], cnt;

void add(int u, int v, int w) {
    e[++cnt] = { v, w, head[u] };
    head[u] = cnt;
}

int dis[maxn], vis[maxn];

void spfa() {
    memset(dis, 0x3f, sizeof(dis));
    dis[1] = 0;
    queue<int> q;
    q.push(1);
    vis[1] = 1;
    while (!q.empty()) {
        int x = q.front(); q.pop();
        vis[x] = 0;
        for (int i = head[x]; i; i = e[i].nxt) {
            int y = e[i].v, z = e[i].w;
            if (dis[y] > dis[x] + z) {
                dis[y] = dis[x] + z;
                if (!vis[y]) q.push(y), vis[y] = 1;
            }
        }
    }
}

signed main() {
    n = read(), m = read();
    for (int i = 1; i <= n; i++) {
        int s = read(), t = read();
        add(m + s, m + t, 1);
        add(s, m + s, 0), add(m + t, t, 0);
    }
    for (int i = 1; i < m; i++) add(i + 1, i, 0);
    spfa();
    cout << dis[m];
}