n,V,c=map(int,input().split())
dp=[-10**9]*(V+1)
dp[0]=0
for _ in range(n):
  v,w=map(int,input().split())
  for s in range(v):
    mx=-10**9
    for i in range(s,V+1,v):
      mx,dp[i]=max(dp[i]+c,mx),max(dp[i],mx)
      mx+=w
print(max(dp))