#include<stdio.h>
#include<stdlib.h>

typedef long long int int64;

#define MIN(a,b) ((a)<(b)?(a):(b))

typedef struct item{
  int a,b;
} node;

int cmp(const void *a,const void *b){
  node *p=(node *)a;
  node *q=(node *)b;
  return q->b-p->b;
}

void run(void){
  int n;
  scanf("%d",&n);
  node *p=(node *)calloc(n,sizeof(node));
  int i;
  for(i=0;i<n;i++){
    int a,b;
    scanf("%d%d",&a,&b);
    p[i]=(node){a,b};
  }
  qsort(p,n,sizeof(node),cmp);
  int len=n/3*2+n%3;
  int64 *dp=(int64 *)calloc(len+1,sizeof(int64));
  for(i=1;i<=len;i++) dp[i]=1000000000000000LL;
  for(i=0;i<n;i++){
    for(int j=len-1;j>=0;j--){
      dp[j+1]=MIN(dp[j+1],dp[j]+p[i].a+p[i].b*j);
    }
  }
  printf("%lld\n",dp[len]);
}

int main(void){
  run();
  return 0;
}