#include <bits/stdc++.h>
using namespace std;
#define int long long
struct node {
int s, e, m, a, b, c, ab, bc, ac, abc, lza, lzb, lzc;
node *l, *r;
node(int _s, int _e) {
s = _s, e = _e, m = (s+e)/2, a = b = c = ab = bc = ac = abc = lza = lzb = lzc = 0;
if(s != e) {
l = new node(s, m);
r = new node(m+1, e);
}
}
void prop() {
if(lza) { // set
a = lza;
ab = lza * b;
ac = lza * c;
abc = lza * bc;
if(s != e) {
l->lza = lza;
r->lza = lza;
}
lza = 0;
}
if(lzb) { // set
b = lzb;
ab = lzb * a;
bc = lzb * c;
abc = lzb * ac;
if(s != e) {
l->lzb = lzb;
r->lzb = lzb;
}
lzb = 0;
}
if(lzc) { // add
c += lzc;
ac += lzc * a;
bc += lzc * b;
abc += lzc * ab;
if(s != e) {
l->lzc += lzc;
r->lzc += lzc;
}
lzc = 0;
}
}
void rseta(int x, int y, int val) {
prop();
if(x <= s && e <= y) {
lza = val; return;
} else if(x > m) r->rseta(x, y, val);
else if(y <= m) l->rseta(x, y, val);
else l->rseta(x, y, val), r->rseta(x, y, val);
l->prop(); r->prop();
a = max(l->a, r->a);
b = max(l->b, r->b);
c = max(l->c, r->c);
ab = max(l->ab, r->ab);
bc = max(l->bc, r->bc);
ac = max(l->ac, r->ac);
abc= max(l->abc, r->abc);
}
void rsetb(int x, int y, int val) {
prop();
if(x <= s && e <= y) {
lzb = val; return;
} else if(x > m) r->rsetb(x, y, val);
else if(y <= m) l->rsetb(x, y, val);
else l->rsetb(x, y, val), r->rsetb(x, y, val);
l->prop(); r->prop();
a = max(l->a, r->a);
b = max(l->b, r->b);
c = max(l->c, r->c);
ab = max(l->ab, r->ab);
bc = max(l->bc, r->bc);
ac = max(l->ac, r->ac);
abc= max(l->abc, r->abc);
}
void raddc(int x, int y, int val) {
prop();
if(x <= s && e <= y) {
lzc += val; return;
} else if(x > m) r->raddc(x, y, val);
else if(y <= m) l->raddc(x, y, val);
else l->raddc(x, y, val), r->raddc(x, y, val);
l->prop(); r->prop();
a = max(l->a, r->a);
b = max(l->b, r->b);
c = max(l->c, r->c);
ab = max(l->ab, r->ab);
bc = max(l->bc, r->bc);
ac = max(l->ac, r->ac);
abc= max(l->abc, r->abc);
}
int bsa(int x) { // find last element a > x
prop();
if(s == e) return s;
else if(r->a > x) return r->bsa(x);
else return l->bsa(x);
}
int bsb(int x) {
prop();
if(s == e) return s;
else if(r->b > x) return r->bsb(x);
else return l->bsb(x);
}
} *root;
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, ans = 0;
cin >> n;
int a[n], b[n];
for(int i = 0; i < n; i++) cin >> a[i] >> b[i];
root = new node(0, n-1);
for(int i = n-1; i >= 0; i--) {
root->raddc(i, n-1, 1);
root->rseta(i, max(i, root->bsa(a[i])), a[i]);
root->rsetb(i, max(i, root->bsb(b[i])), b[i]);
ans = max(ans, root->abc);
}
cout << ans << '\n';
}
