x = list(map(int, input()))
l = len(x)

x.sort(reverse=True)
for i in range(l - 1, 0, -1):
    if x[i] != x[i-1]:
        x[i], x[i-1] = x[i-1], x[i]
        break

else:
    print(-1)
    exit()

print(*x, sep="")