#include <bits/stdc++.h>

using namespace std;

char buf[(1<<21)+5],*p1,*p2;
#define getchar() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)

inline int read() {
	int x = 0, f = 0; char ch = getchar();
	while (!isdigit(ch)) f |= (ch == '-'), ch = getchar();
	while (isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
	return f ? -x : x;
}

const int N = 5e5 + 500; int f[N];
int ma = 0;
signed main() {
	// freopen("lis.in", "r", stdin);
	// freopen("1.out", "w", stdout);
	int T = read(); while (T--) {
		int l = read(), r = read();
        while (ma < r) ++ma, f[ma] = f[ma - 1];
        for (int i = r; i >= l; --i) f[i] = f[i - 1] + 1;
        for (int i = r + 1; i <= ma; ++i) {
            if (f[i] >= f[r]) break; f[i] = f[r]; }
	} cout << f[ma];
	return 0;
}