#include<iostream>#include<cstdio>#include<cstdlib>#include<cstring>#include<cmath>#include<algorithm>#include<queue>#include<time.h>using namespace std;long long s[100005];int main(){ long long n,i,ans; while(cin>>n) { if(n==0) { break; } for(i=0;i<n;i++) { cin>>s[i]; } ans=0; for(i=0;i<n-1;i++) { if(s[i]>0) { ans+=s[i]; s[i+1]+=s[i]; } else { ans-=s[i]; s[i+1]+=s[i]; } } cout<<ans<<endl; } return 0;}
