Memory Limit exception c++ vector

Memory Limit exception c++ vector

I am trying to read integer values from text file into a vector
Input file ip1.txt has the following data-
4
-1000 -2000 -3000 -4000
int maxsub(vector<int> a, int size)
{
a.erase(a.begin());
vector<int> sum;
for(vector<int>::iterator w=a.begin();w<=a.begin()+size-1;++w)
{
int j;
int s=*w;
for(int t=0;t<=size-1;t++)
{
j=s+a[t];
sum.push_back(j);
}
a.pop_back();
}
std::sort(sum.begin(),sum.end());
int u=sum.size()-1;
int m=sum.at(u);
return m;
}
int main()
{
std::vector<int>
nums((std::istream_iterator<int>(std::cin)),std::istream_iterator<int>());
int k=nums[0];
int u=maxsub(nums,k);
cout<<u<<endl;
}
I am getting Warning message as 'Memory Limit Exceeded'
How can i resrict vector to read only till -4000 in the input file,I am
using file redirection *./123 < ip1.txt *