#include<cstdio>
#define MAXN 100005
long long a[MAXN];
int main() {
	int n,k;
	long long l,r,mid,s,tot;
	scanf("%d %d",&n,&k);
	for(int i=1;i<=n;++i) scanf("%lld",&a[i]);
	l=0; r=1e14+k;
	while(l<=r) {
		mid=(l+r)>>1;
		s=0ll; tot=0ll;
		for(int i=1;i<=n;++i) {
			if(a[i]+s>=mid) continue;
			tot+=(mid-a[i]-s-1)/i+1;
			s+=((mid-a[i]-s-1)/i+1)*i;
		}
		if(tot<=k) l=mid+1;
		else r=mid-1;
	}
	printf("%lld",l-1);
	return 0;
}