#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll N=1e6 + 8;
const int maxn = 2e5;
ll t, aux;
ll slope[N]={0}, c[N]={0};
ll f(ll a, ll b, ll x)
{ return a*x+b;}
void add_line(ll ms, ll con, int v = 1, ll l = 0, ll r = N/4) {
ll m= l + (r-l)/2;
bool lef = f(ms,con,l) < f(slope[v],c[v],l);
bool mid = f(ms,con,m) < f(slope[v],c[v],m);
if(mid) {
swap(slope[v], ms);
swap(c[v],con);
}
if(r - l == 1) {
return;
} else if(lef != mid) {
add_line(ms, con, 2 * v, l, m);
} else {
add_line(ms,con, 2 * v + 1, m, r);
}
}
ll get(ll x, int v = 1, ll l = 0, ll r = N/4) {
ll m = l + (r-l) / 2;
if(r - l == 1)
{
t=slope [v];
return f(slope[v],c[v],x);
}
else if(x>m) {
aux= get(x, 2 * v, l, m);
if (f(slope[v],c[v],x)>=aux)
{t=slope[v];
return f(slope[v],c[v],x); }
} else {
aux= get(x, 2 * v + 1, m, r);
if(f(slope[v], c[v], x)> aux)
{
t=slope [v];
return f(slope[v], c[v], x);
}
}
return aux;
}
int n;
long long a[N], d[N];
void load() {
scanf("%d", &n);
for (int i = 1; i <=n; ++i) {
scanf("%lld%lld", &a[i], &d[i]);
}
}
void process() {
long long cost = a[1];
add_line(-d[1], a[1]+d[1]);
for (ll i = 2; i <= n; ++i)
{
cost = a[i]+get(i);
if (i<n)
add_line(-d[i], cost+i*d[i]);
}
printf("%lld",cost+t);
}
int main() {
load();
process();
return 0;
}
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