#include <bits/stdc++.h>
#define ll long long
#define N 100010
using namespace std;

ll f[N],g[N],a[N];
char op,lst;

int main(){
    int n,x,y=0,i,cnt=0;
    cin>>n;
    ll ans=0;
    for(i=1;i<=n;++i){
        cin>>x;lst=op;
        if(i<n) cin>>op;
        if(lst=='-'){
            x=-x;
            a[++cnt]=x;
        }
        if(y<=0 && x>0) cnt++,a[cnt]=x;
        if(y>0 && x>0) a[cnt]+=x;
        y=x;
    } f[1]=a[1];
    for(i=cnt;i>=1;--i) g[i]=g[i+1]+abs(a[i]);
    for(i=2;i<=cnt;++i) f[i]=f[i-1]+a[i];
    ans=f[cnt];
    for(i=1;i<cnt;++i)
        if(a[i+1]<0) ans=max(ans,f[i+1]-a[i+2]+g[i+3]);
    cout<<ans; 
} 