#calculator
def calculate(x , y , op):
    if op == '+' :
        z = x  + y
    elif op == '-' :
        z = x - y
    elif op == '*' :
        z = x * y
    elif op == '//' :
        if y!=0:
            z = x // y
        else:
            print "division not possible"
    return z

print calculate(9 , 9 , '//')
print calculate(11 , 0 , '//')