N = input()
L = len(N)
stack = []
for c in N:
    if c in '45':
        stack.append(c)
    elif c > '5':
        while len(stack) < L:
            stack.append('5')
        break
    else:
        while stack and stack[-1]=='4':
            stack.pop()
        if len(stack)==0:
            stack = ['5']*(L-1)
        else:
            stack.pop()
            stack.append('4')
            while len(stack) < L:
                stack.append('5')
        break
print(''.join(stack))