import sys
input=lambda: sys.stdin.readline().rstrip()
n=int(input())
AB=[]
for _ in range(n):
  a,b=map(int,input().split())
  AB.append((a,b))
AB.sort(key=lambda x:x[1],reverse=True)
DP=[float("inf")]*(n+1)
DP[0]=0
for i in range(n):
  a,b=AB[i]
  for j in range(1,i+2)[::-1]:
    DP[j]=min(DP[j],DP[j-1]+(j-1)*b+a)
nn=n//3*2+n%3
print(DP[nn])