def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    N = int(input[idx]); idx += 1
    V = int(input[idx]); idx += 1
    C = int(input[idx]); idx += 1
    
    items = []
    for _ in range(N):
        v = int(input[idx]); idx += 1
        w = int(input[idx]); idx += 1
        items.append((v, w))
    
    INF = float('-inf')
    dp = [[INF] * (N + 1) for _ in range(V + 1)]
    dp[0][0] = 0
    
    for v, w in items:
        # Step 1: Include exactly one item of this type
        for j in range(V, v - 1, -1):
            for k in range(N, -1, -1):
                if dp[j - v][k] != INF:
                    if dp[j][k + 1] < dp[j - v][k] + w:
                        dp[j][k + 1] = dp[j - v][k] + w
        # Step 2: Include any number of items (including zero) of this type
        for j in range(v, V + 1):
            for k in range(N + 1):
                if dp[j - v][k] != INF:
                    if dp[j][k] < dp[j - v][k] + w:
                        dp[j][k] = dp[j - v][k] + w
    
    max_satisfaction = 0
    for j in range(V + 1):
        for k in range(N + 1):
            if dp[j][k] != INF:
                satisfaction = dp[j][k] + C * k
                if satisfaction > max_satisfaction:
                    max_satisfaction = satisfaction
    print(max_satisfaction)

if __name__ == '__main__':
    main()