#include<stdio.h>
#include<algorithm>
#define N 1000010

int n,k,m[N];
int main()
{
	int sum = 0;
	scanf("%d%d",&n,&k);
	for(int i=0;i<n;i++)
	{
		scanf("%d",&m[i]);
		sum += (k - m[i]);
	}
	printf("%d",std::max(std::min(k-sum,n),0));
	return 0;
}