#include <bits/stdc++.h>
const int N=2e5+10;
using namespace std;
typedef long long ll;
bool debug1;
int n,l=1,r;
int q[N];
ll sum,ans,f[N],w[N],dd[N],d[N],s[N];
bool debug2;
double slope(int i,int j){
	return 1.0*(s[i]*d[i]-s[j]*d[j])/(s[i]==s[j]?1e-9:s[i]-s[j]);
}
int main(){
//	freopen("data.in","r",stdin);
//	freopen("my.out","w",stdout);
//	cout<<((&debug2-&debug1)/1024.0/1024.0)<<endl;
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%lld%lld",&w[i],&dd[i]);
		s[i]=s[i-1]+w[i];
	}
	for(int i=n;i>=1;i--)
		d[i]=d[i+1]+dd[i];
	for(int i=1;i<=n;i++)
		sum+=d[i]*w[i];
	for(int i=1;i<=n;i++){
		while(l<r&&slope(i-1,q[r])>=slope(q[r],q[r-1]))
			r--;
		q[++r]=i-1;
		while(l<r&&slope(q[l+1],q[l])>=d[i])
			l++;
		int j=q[l];
		f[i]=sum-(s[j]*d[j]-s[j]*d[i]+s[i]*d[i]);
	}
	ans=f[1];
	for(int i=1;i<=n;i++)
		ans=min(ans,f[i]);
	printf("%lld",ans);
	return 0;
}