N,V,C = map(int,input().split())

from collections import defaultdict
d = defaultdict(int)
for _ in range(N):
    v,w = map(int,input().split())
    d[v] = max(d[v],w)
dp = [0] * (V + 1)
for v,w in d.items():
    nx = dp.copy()
    for i in range(V + 1):
        for j in range(1,(V - i) // v + 1):
            nx[i + j * v] = max(nx[i + j * v],dp[i] + C + w * j)
        
    dp = nx
print(max(dp))