N = int(input()) W = list(map(int,input().split(" "))) sum = 0 for i in range(N): sum += W[i] if sum % 2 == 1: print("impossible") dp = [[False for _ in range(sum + 1)]for __ in range(N+1)] for i in range(N): dp[i][0] = True for i in range(1,N): for j in range(1,sum): dp[i][j] = dp[i-1][j] or dp[i-1][j-W[i]] for i in range(N): if dp[i][int(sum/2)]: print("possible") exit() print("impossible")