runner_up.py

if __name__ == '__main__':
    n = int(raw_input())
    arr = map(int, raw_input().split())
    
    maximum = arr[0]
    last_max = None
    
    for i in range(1, len(arr)):
        #знаходимо максимальний максимум
        if arr[i] > maximum:
            if maximum != last_max:
                last_max = maximum
            maximum = arr[i]
        
        #знаходимо друний максимум Runner-Up
        if last_max == None:
            if arr[i] != maximum:
                last_max = arr[i] 
        else:
            if arr[i] > last_max and arr[i]  < maximum:
                last_max = arr[i]
    
    print(last_max)