(a/b)%MOD

int bigmod(long long a,long long p)
{
    long long ret = 1;
    while(p) {
        if(p & 1) ret = ret * a % mod;
        a = a * a % mod;
        p >>= 1;
    }
    return ret;
}

(a/b)%MOD = mod_mul(a,bigmod(b,MOD-2))