hdu 4990 Reading comprehension

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <string>
#include <queue>
#include <map>
#include <set>
#define lson l, m, rt << 1
#define rson m + 1, r, rt << 1|1
using namespace std;
typedef long long LL;
const int N = 100005;
LL n, m, nn, mm;
LL pow_mod(LL b)
{
    LL res = 1, a = 2;
    while(b) {
        if(b & 1) res = res * a % m;
        a = (a % m) * a % m;
        b >>= 1;
    }
    return res;
}
LL sum1(LL k)
{
    if(k == 1) return 1;
    LL tmp, now;
    if(k & 1) tmp = pow_mod(k - 1);
    else tmp = pow_mod(k);

    now = sum1(k >> 1) % m;
    LL res = (now % m + (now * tmp) % m) % m;
    if(k & 1) res = res + pow_mod(k * 2 - 2) % m;
    return res;

}
LL sum2(LL k)
{
    if(k == 1) return 2;
    LL tmp, now;
    if(k & 1) tmp = pow_mod(k - 1);
    else tmp = pow_mod(k);

    now = sum2(k >> 1) % m;
    LL res = (now % m + (now * tmp) % m) % m;
    if(k & 1) res = res + pow_mod(k * 2 - 1) % m;
    return res;
}
int main()
{
    while(~scanf("%lld%lld", &n, &m))
    {
        LL ans = 0;
        if(n & 1) {
            nn = (n + 1) >> 1;
            ans = sum1(nn);
            printf("%lld\n", ans % m);
        }
        else {
            mm = (n) >> 1;
            ans = sum2(mm);
            printf("%lld\n", ans % m);
        }
    }
}