WA求助

#include<iostream>
#include<cmath>
#include<cstring>
#include<string>
#include<algorithm>
#include<cstdio>
using namespace std;
long long n,m,a,maxn,minn=114514;
long long ksm(long long a, long long n)
{
    if (n == 0)
        return 1;
    else if (n % 2 == 1)
        return ksm(a, n - 1) * a;
    else
    {
        int temp = ksm(a, n / 2);
        return temp * temp;
    }
}
int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)
	{
		scanf("%lld",&a);
		maxn=max(maxn,a);
		minn=min(minn,a);
	}
	if(maxn<=1)
	{
		cout<<ksm(2,(m-1))*(maxn+2)-minn;
	}
	else cout<<ksm(2,m)*maxn-minn;
    return 0;
}