#include<bits/stdc++.h>
#define MAXN 200005
#define LL long long
using namespace std;

LL n,sum,ans=-0x3f3f3f3f,all=0x3f3f3f3f,maxn=-0x3f3f3f3f;
LL a[MAXN],dp[MAXN],f[MAXN];

int main()
{
	scanf("%lld",&n);
	for(int i=1;i<=n;i++)
		scanf("%lld",&a[i]),sum+=a[i],maxn=max(maxn,a[i]);
	for(int i=1;i<=n;i++)
		dp[i]=max(0*1ll,dp[i-1])+a[i],ans=max(ans,dp[i]);
	for(int i=1;i<=n;i++)
		f[i]=min(0*1ll,f[i-1])+a[i],all=min(all,f[i]);
	if(all==sum) all-=maxn;
	ans=max(ans,sum-all);
	printf("%lld",ans);
}