#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<queue>
#include<list>
#include<math.h>
#include<vector>
#include<stack>
#include<string>
#include<cstring>
#include<string.h>
using namespace std;
typedef long long LL;
#define ll LL
#define bug printf("*********\n")
#define debug(x) cout<<#x"=["<<x<<"]" <<endl
const int MAXN = 2e4 + 10;
const double eps = 1e-8;
const LL mod = 1000000007;LL sum1[MAXN],sum2[MAXN];
struct node {int x,v;
}a[MAXN];
int lowbit(int x) {return x & -x;
}void update1(int x,int y) {for(int i = x; i <= MAXN; i += lowbit(i))sum1[i] += y;
}
void update2(int x,int y) {for(int i = x; i <= MAXN; i += lowbit(i))sum2[i] += y;
}LL getsum1(int x) {LL ans = 0;for(int i = x; i; i -= lowbit(i))ans += sum1[i];return ans;
}LL getsum2(int x) {LL ans = 0;for(int i = x; i; i -= lowbit(i))ans += sum2[i];return ans;
}void init() {memset(sum1,0,sizeof sum1);memset(sum2,0,sizeof sum2);
}
bool cmp(node x,node y) {return x.v < y.v;
}
int main()
{init();int n;int M = 2e4;scanf("%d",&n);for(int i = 1; i <= n; i++)scanf("%d %d",&a[i].v, &a[i].x);sort(a + 1, a + 1 + n,cmp);LL ans = 0;for(int i = 1; i <= n; i++) {
//        debug(getsum1(a[i].x));
//        debug(getsum2(a[i].x));
//        debug(getsum1(M) - getsum1(a[i].x));
//        debug(getsum2(M) - getsum2(a[i].x));ans += a[i].v * (getsum1(a[i].x) * a[i].x - getsum2(a[i].x));
//        debug(ans);ans += a[i].v * ((getsum2(M) - getsum2(a[i].x)) - (getsum1(M) - getsum1(a[i].x)) * a[i].x);update1(a[i].x,1);update2(a[i].x,a[i].x);
//        debug(ans);
    }printf("%lld\n",ans);
}