n=int(input())
x=[tuple(map(int,input().split())) for i in range(n)]
x.sort(key=lambda x:x[1],reverse=True)
dp=[1<<60]*(n+1)
dp[0]=0;p=0
for i,j in x:
    dp2=[1<<60]*len(dp)
    for l in range(p+1):
        dp2[l]=min(dp2[l],dp[l]+(p-l)*j+i)
        dp2[l+1]=min(dp2[l+1],dp[l])
    p+=1;dp=dp2
print(dp[n//3])