import sys
 
def main():
    # Lê a entrada de forma rápida e segura
    dados = sys.stdin.read().split()
 
    if not dados:
        return
 
    # Atribui os valores da largura e comprimento usando os caracteres Unicode
    x = int(dados[0])
    y = int(dados[1])
 
    # Cenário A: Marcadores "em pé" (Largura intacta, comprimento fatiado por 7)
    cenario_a = x * (y // 7)
 
    # Cenário B: Marcadores "deitados" (Largura fatiada por 7, comprimento intacto)
    cenario_b = (x // 7) * y
 
    # O juiz online espera apenas o maior resultado possível
    print(max(cenario_a, cenario_b))
 
if __name__ == '__main__':
    main()

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