f[i]=f[j]+a[i]*b[j+]

-a[i]*b[j+]+f[i]=f[j]
 k      x   +  b = y

/**************************************************************

    Problem: 1597

    User: yekehe

    Language: C++

    Result: Accepted

    Time:104 ms

    Memory:3268 kb

****************************************************************/

#include <cstdio>

#include <algorithm>

using namespace std;

char tc()

{

    static char tr[],*A=tr,*B=tr;

    return A==B&&(B=(A=tr)+fread(tr,,,stdin),A==B)?EOF:*A++;

}

int read()

{

    char c;while(c=tc(),c<''||c>'');

    int x=c-'';while(c=tc(),c>=''&&c<='')x=x*+c-'';

    return x;

}

int N,tot;

struct node{long long x,y;}a[],c[];

inline int cmp(node x,node y){return x.x<y.x;}

long long l[],h,t,f[];

double X(int x){return c[x+].y;}

double Y(int y){return f[y];}

double get(int x,int y){return (Y(y)-Y(x))/(X(y)-X(x));}

int main()

{

    N=read();

    register int i;

        for(i=;i<=N;i++)a[i].x=read(),a[i].y=read();

    sort(a+,a+N+,cmp);

        for(i=;i<=N;i++){

            while(tot&&a[i].y>=c[tot].y)tot--;

            c[++tot]=a[i];

        }

    h=t=;

        for(i=;i<=tot;i++){

            while(h<t&&-c[i].x<get(l[h],l[h+]))h++;

            int j=l[h];f[i]=f[j]+c[i].x*c[j+].y;

            while(h<t&&get(l[t-],l[t])<get(l[t],i))t--;

            l[++t]=i;

        }

    printf("%lld",f[tot]);

    return ;

}