A.Counterexample（CodeforcesRound#275(div2)

Note

In the first sample pair (2,?4) is not coprime and pairs (2,?3) and (3,?4) are.

In the second sample you cannot form a group of three distinct integers, so the answer is -1.

In the third sample it is easy to see that numbers 900000000000000009 and 900000000000000021 are divisible by three.

找出3个数，前两个的最大公约数为1，后两个最大公约数为1，第1个和第3个的最大公约数不为1.

由于题目中说了，r-l

代码：

#include  
#include  
#include 
#include  
using namespace std;
long long gcd(long long a,long long b)
{
    return b==0?a:gcd(b,a%b);
}
int main()
{
    long long l,r;
    long long x,y,z;
    int sign=0;
    scanf("%I64d%I64d",&l,&r);
    for(long long i=l;i 

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