def _FACT_TABLE():
    facts=[0, 1, 2]
    def _fact(n):
        if n<len(facts)-1:
            return facts[n]
        for i in range(len(facts), n+1):
            facts.append(facts[i-1]*i)
        return facts[n]
    return _fact

_fact=_FACT_TABLE()


def _sort(symbs):
    p_s=[x//2 for x in symbs.values() if x//2 > 0 ]
    m_s=[x%2 for x in symbs.values() if x%2 > 0 ]
    return p_s, m_s
   
   
def _to_symbs(l, r):
    symbs={}
    for i in range(l-1,r):
        symbs[S[i]]=symbs.get(S[i],0)+1
    return symbs
    
    
def _calculate(p_s, m_s):
    res=_fact(max(sum(p_s), 1))
    for x in p_s:
        res=int(res/_fact(x))
    res=res*max(len(m_s),1)
    return res
    
    
def answerQuery(l, r):
    # Return the answer for this query modulo 1000000007.
    symbs=_to_symbs(l,r)
    if len(symbs)==1:
        return 1
    p_s, m_s=_sort(symbs)
    return _calculate(p_s, m_s)