Envío 605

Código

#include <iostream>
#include <vector>
#include <cassert>
#include <algorithm>

using namespace std;

void solve(const vector<int> &a, int n, int sum) {
  for (int i = 0; i < n; ++i) {
    int left = 0;
    for (int j = i - 1; j >= 0; --j) {
      left += a[j];
    }
    int right = sum - left;
    if (left > 0 and right < 0) {
      cout << i << endl;
      return;
    }
  }
  cout << "Impossible" << endl;
}

int main() {
  int n;
  cin >> n;
  assert(2 <= n and n <= 500000);
  vector<int> a(n);
  int sum = 0;
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    sum += a[i];
  }
  solve(a, n, sum);
  return 0;
}