import numpy as np
X = list(map(int,input()))
X.sort(reverse=True)
npX = np.array(X)
mins = np.count_nonzero(npX==X[-1])
#print(npX)
#print(mins)
if X[0] == X[-1]:
    print(-1)
else:
    ans = X[:len(X)-(mins+1)]+[X[-1]]+[X[-(mins+1)]]+[X[-1]]*(mins-1)
    if ans[0] == 0:
        print(-1)
    else:
        print("".join(map(str,list(ans))))