HDU 5666 Segment

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<map>
#include<algorithm>
using namespace std;

long long q,p;

long long Cheng(long long a,long long b)
{
    long long res=0;
    while(b)
    {
        if(b%2==1) res=(res+a)%p,b--;
        a=(a*2)%p,b=b/2;
    }
    return res;
}

int main()
{
    int T; scanf("%d",&T);
    while(T--)
    {
        scanf("%lld%lld",&q,&p);
        long long x=q-2,y=q-1; y=y/2;
        printf("%lld\n",Cheng(x,y));
    }
    return 0;
}