N, M, C = map(int, input().split())
VW = [list(map(int, input().split())) for _ in range(N)]

dp = [[-float('inf')] * (M+1) for _ in range(N+1)]
dp[0][0] = 0
for i in range(N):
    v, w = VW[i]
    for j in range(M+1):
        m = j
        cnt = 0
        c = 0
        while m <= M:
            dp[i+1][m] = max(dp[i+1][m], dp[i][j]+w*cnt + c)
            cnt += 1
            c = C
            m = j + v * cnt
ans = max(dp[N])
print(ans)