数学 FZU 2074 Number of methods

题目传送门

 /*
     数学：假设取了第i个，有C(n-1)(i-1)种取法
         则ans = sum (C(n-1)(i-1)) (1<i<=n) 即2^(n-1)
 */
 #include <cstdio>
 #include <algorithm>
 #include <cstring>
 #include <cmath>
 using namespace std;

 typedef long long ll;
 const int MAXN = 1e4 + ;
 const int INF = 0x3f3f3f3f;
 const int MOD = ;

 int main(void)        //FZU 2074 Number of methods
     int n;
     while (scanf ("%d", &n) == )
     {
         ll sum = ;
         for (int i=; i<n; ++i)
         {
             sum = sum *  % MOD;
         }
         printf ("%I64d\n", sum);
     }

     return ;
 }