import sys
import pypyjit
import itertools
import heapq
import math
from collections import deque, defaultdict
import bisect

input = sys.stdin.readline
sys.setrecursionlimit(10 ** 6)
pypyjit.set_param('max_unroll_recursion=-1')


def index_lt(a, x):
    'return largest index s.t. A[i] < x or -1 if it does not exist'
    return bisect.bisect_left(a, x) - 1


def index_le(a, x):
    'return largest index s.t. A[i] <= x or -1 if it does not exist'
    return bisect.bisect_right(a, x) - 1


def index_gt(a, x):
    'return smallest index s.t. A[i] > x or len(a) if it does not exist'
    return bisect.bisect_right(a, x)


def index_ge(a, x):
    'return smallest index s.t. A[i] >= x or len(a) if it does not exist'
    return bisect.bisect_left(a, x)


N = int(input())
P = [tuple(map(int, input().split())) for _ in range(N)]
P.sort(key=lambda x: x[1], reverse=True)

INF = 1 << 40
dp = [[INF for _ in range(N // 3 + 1)] for _ in range(N + 1)]
dp[0][0] = 0
for i in range(1, N + 1):
    a, b = P[i - 1]
    for j in range(N // 3 + 1):
        if j > 0:
            dp[i][j] = min(dp[i - 1][j - 1], dp[i - 1][j] + a + b * (i - 1 - j))
        else:
            dp[i][j] = dp[i - 1][j] + a + b * (i - 1 - j)
print(min(dp[N]))