import math

def minimal_punches(H, W, L_A, L_B, K_A, K_B):
    min_total = float('inf')
    A_max = (H + L_A - 1) // L_A  # ceil(H / L_A)
    for a in range(0, A_max + 1):
        R = min(a * L_A, H)
        B_lim = W // L_B
        
        # Case 1: B <= B_lim, C = B*L_B <= W
        denominator_case1 = K_B + R * L_B
        required_case1 = H * W - a * K_A
        possible_B_case1 = None
        case1_possible = False
        
        if denominator_case1 == 0:
            if required_case1 <= 0:
                possible_B_case1 = 0
                case1_possible = possible_B_case1 <= B_lim
            else:
                case1_possible = False
        else:
            if required_case1 <= 0:
                possible_B_case1 = 0
                case1_possible = possible_B_case1 <= B_lim
            else:
                possible_B_case1 = (required_case1 + denominator_case1 - 1) // denominator_case1
                possible_B_case1 = max(0, possible_B_case1)
                case1_possible = possible_B_case1 <= B_lim
        
        # Case 2: B >= ceil(W / L_B), C = W
        B2_candidate = (W + L_B - 1) // L_B
        required_case2 = W * (H - R)
        remaining = required_case2 - a * K_A
        
        if remaining <= 0:
            possible_B_case2 = B2_candidate
            case2_possible = True
        else:
            if K_B == 0:
                possible_B_case2 = float('inf')
                case2_possible = False
            else:
                possible_B_case2 = max(B2_candidate, (remaining + K_B - 1) // K_B)
                case2_possible = (a * K_A + possible_B_case2 * K_B) >= required_case2
        
        # Case 3: B=0, check if possible
        case3_possible = (a * K_A >= H * W)
        possible_B_case3 = 0
        
        # Collect all possible B options
        candidates_B = []
        if case1_possible:
            candidates_B.append(possible_B_case1)
        if case2_possible and possible_B_case2 != float('inf'):
            candidates_B.append(possible_B_case2)
        if case3_possible:
            candidates_B.append(possible_B_case3)
        
        if not candidates_B:
            continue
        
        current_B = min(candidates_B)
        total = a + current_B
        
        if total < min_total:
            min_total = total
    
    return min_total if min_total != float('inf') else 0

# Read input
H, W, L_A, L_B, K_A, K_B = map(int, input().split())

# Compute result
result = minimal_punches(H, W, L_A, L_B, K_A, K_B)

# Output the result
print(result)