import io
import sys
from collections import defaultdict, deque, Counter
from itertools import permutations, combinations, accumulate
from heapq import heappush, heappop
from bisect import bisect_right, bisect_left
from math import gcd
import math

_INPUT = """\
6
3 4 2
1 2
1 3
2 0
5 1 3
2 0
2 0
1 4
1 4
1 4
1 1 1
1 1
2 999999999999999999 1
1 1
2 0
"""

def input():
  return sys.stdin.readline()[:-1]

def solve(test):
  N,P,K=map(int, input().split())
  dp=[0]*(N+1)*(K+1)
  dp[0]=P
  for i in range(N):
    T,B=map(int, input().split())
    for j in range(K+1):
      dp[(i+1)*(K+1)+j]=dp[i*(K+1)+j]
      if j>0:
        if T==1:
          dp[(i+1)*(K+1)+j]=max(dp[(i+1)*(K+1)+j],dp[i*(K+1)+j-1]+B)
        else:
          dp[(i+1)*(K+1)+j]=max(dp[(i+1)*(K+1)+j],dp[i*(K+1)+j-1]*2)
      if dp[(i+1)*(K+1)+j]>10**18:
        dp[(i+1)*(K+1)+j]=10**18+1
  print(dp[-1] if dp[-1]<=10**18 else -1)

def random_input():
  from random import randint,shuffle
  N=randint(1,10)
  M=randint(1,N)
  A=list(range(1,M+1))+[randint(1,M) for _ in range(N-M)]
  shuffle(A)
  return (" ".join(map(str, [N,M]))+"\n"+" ".join(map(str, A))+"\n")*3

def simple_solve():
  return []

def main(test):
  if test==0:
    solve(0)
  elif test==1:
    sys.stdin = io.StringIO(_INPUT)
    case_no=int(input())
    for _ in range(case_no):
      solve(0)
  else:
    for i in range(1000):
      sys.stdin = io.StringIO(random_input())
      x=solve(1)
      y=simple_solve()
      if x!=y:
        print(i,x,y)
        print(*[line for line in sys.stdin],sep='')
        break

#0:提出用、1:与えられたテスト用、2:ストレステスト用
main(0)