import sys
input = sys.stdin.readline


N,V,C=map(int,input().split())
VW=[list(map(int,input().split())) for _ in range(N)]
INF=float("inf")

dp = [-INF]*(V+1)
dp[0]=0
for v,w in VW:
    dp2 = [-INF]*(V+1)
    dp2[0] = 0
    for i in range(V+1):
        dp2[i] = dp[i]
        if i-v>=0:
            dp2[i] = max(dp2[i], dp[i-v]+w+C, dp2[i-v]+w)
    dp = dp2
print(max(dp))