#include <bits/stdc++.h>
using namespace std;
#define maxn 2000000
#define INF 99999999
int n, m, mn[maxn], mark[maxn];
int ans = INF;int read()
{int x = 0, k = 1;char c; c = getchar();while(c < '0' || c > '9') { if(c == '-') k = -1; c = getchar(); }while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();return x * k;
}struct node
{int l, r;friend bool operator <(const node& a, const node& b){ return a.r > b.r; }
}P[maxn];void push_down(int p)
{if(!mark[p]) return;mark[p << 1] += mark[p], mark[p << 1 | 1] += mark[p];mn[p << 1] += mark[p], mn[p << 1 | 1] += mark[p];mark[p] = 0;
}void Update(int p, int l, int r, int L, int R, int x)
{if(L <= l && R >= r) { mn[p] += x; mark[p] += x; return; }if(L > r || R < l) return;int mid = (l + r) >> 1;push_down(p);Update(p << 1, l, mid, L, R, x); Update(p << 1 | 1, mid + 1, r, L, R, x);mn[p] = min(mn[p << 1], mn[p << 1 | 1]);
}void Build(int p, int l, int r)
{if(l == r) { mn[p] = l; return; }int mid = (l + r) >> 1;Build(p << 1, l, mid), Build(p << 1 | 1, mid + 1, r);mn[p] = min(mn[p << 1], mn[p << 1 | 1]);
}int Query(int p, int l, int r, int x)
{if(l == r) return mn[p];int mid = (l + r) >> 1;push_down(p);if(x <= mid) return Query(p << 1, l, mid, x);else return Query(p << 1 | 1, mid + 1, r, x);
}int main()
{n = read(), m = read(); for(int i = 1; i <= n; i ++) P[i].l = read(), P[i].r = read();sort(P + 1, P + 1 + n);int now = 1; Build(1, 0, m);for(int i = m + 1; i >= 0; i --){while(now <= n && P[now].r >= i) Update(1, 0, m, P[now].l, m, -1), now ++;Update(1, 0, m, i, m, -1);ans = min(ans, (m - i + 1) + mn[1]);}if(ans < 0) printf("%d\n", -ans);else printf("0\n");return 0;
}