import sys
input = lambda: sys.stdin.readline().rstrip()

#  -----------------------  #

n, V, C = map(int, input().split())
vw = [list(map(int, input().split())) for _ in range(n)]

dp = [[-1]*(V+1) for _ in range(n+1)]
dp[0][0] = 0

for i in range(n):
  v, w = vw[i]
  for j in range(V+1):
    if dp[i][j] == -1:
      continue

    dp[i+1][j] = max(dp[i+1][j], dp[i][j])

    if j+v < V+1:
      dp[i+1][j+v] = max(dp[i+1][j+v], dp[i][j]+w+C)
    cnt = 2
    while j+v*cnt < V+1:
      dp[i+1][j+v*cnt] = max(dp[i+1][j+v*cnt], dp[i][j]+w*cnt+C)
      cnt += 1

print(max(dp[n]))