#!/usr/bin/env python3 # written to ensure that the presentation slide strategy is actually correct import sys if __name__ == '__main__': m = int(sys.stdin.readline()) weights = [int(sys.stdin.readline()) for _ in range(m)] unique_weights = sorted(set(weights)) multiplicity = {} for w in weights: multiplicity[w] = multiplicity.get(w, 0) + 1 P = [] for w in unique_weights: P.append((P[-1] if P else 0) + w * multiplicity[w]) answer = None for i, w in enumerate(unique_weights): if P[i] == P[-1] + w * multiplicity[w] - P[i]: answer = w elif P[i] == P[-1] - P[i]: answer = w + 1 assert answer is not None print(answer)