import sys
readline=sys.stdin.readline

N=int(readline())
A,B=[],[]
for i in range(N):
    a,b=map(int,readline().split())
    A.append(a)
    B.append(b)
inf=1<<60
NN=N-N//3
dp=[inf]*(NN+1)
dp[0]=0
for i in sorted([i for i in range(N)],key=lambda i:B[i],reverse=True):
    for n in range(NN,0,-1):
        dp[n]=min(dp[n],dp[n-1]+A[i]+B[i]*(n-1))
ans=dp[NN]
print(ans)