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

vs = [] #値段
ws = [] #価値

for i in range(N):
    v,w = map(int,input().split())
    vs.append(v)
    ws.append(w)

dp = []  #購入したものの価値総計
dp2 = [] #購入したものの種類数
dp3 = [] #満足度

for i in range(N+1):
    dp.append([-1]*(V+1))
    dp2.append([0]*(V+1))
    dp3.append([-1]*(V+1))

dp[0][0] = 0
dp3[0][0] = 0

for i in range(N):
    for ii in range(V,-1,-1):
        if dp[i][ii] != -1:
#            dp[i+1][ii] = max(dp[i][ii],dp[i+1][ii])
#            dp2[i+1][ii] = max(dp2[i][ii],dp2[i+1][ii])
#            dp3[i+1][ii] = max(dp3[i][ii],dp3[i+1][ii])

            tmp = (V-ii)//vs[i] #買える個数

            for iii in range(tmp,0,-1):
                tmp2 = ii+(iii*vs[i])
                tmp3 = dp[i][ii]+(iii*ws[i])
                tmp4 = (dp2[i][ii]+1)*C

                if tmp3+tmp4 > dp3[i+1][tmp2]:
                    dp[i+1][tmp2] = tmp3
                    dp2[i+1][tmp2] = dp2[i][ii]+1
                    dp3[i+1][tmp2] = tmp3+tmp4
            dp[i+1][ii] = max(dp[i][ii],dp[i+1][ii])
            dp2[i+1][ii] = max(dp2[i][ii],dp2[i+1][ii])
            dp3[i+1][ii] = max(dp3[i][ii],dp3[i+1][ii])

ans = 0
for i in dp3[-1]:
    ans = max(ans,i)

print(ans)