1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
//mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
//int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=501000;
ll s[N];
pair<ll,int> p[N];
int rk[N],dp[N],n,c[N];
int query(int x) {
	int s=-(1<<30);
	for (;x;x-=x&-x) s=max(s,c[x]);
	return s;
}

void modify(int x,int s) {
	for (;x<=n+1;x+=x&-x) c[x]=max(c[x],s);
}

int main() {
	scanf("%d",&n);
	for (int i=1;i<=n;i++) {
		int x;
		scanf("%d",&x),s[i]=s[i-1]+x;
	}
	for (int i=0;i<=n;i++) p[i]=mp(s[i],i);
	sort(p,p+n+1);
	rep(i,0,n+1) rk[p[i].se]=i+1;
	for (int i=1;i<=n+1;i++) c[i]=-(1<<30);
	dp[0]=0;
	modify(rk[0],0);
	rep(i,1,n+1) {
		dp[i]=query(rk[i]-1)+1;
		modify(rk[i],dp[i]);
	}
	if (dp[n]>=0) printf("%d\n",n-dp[n]);
	else puts("-1");
}