Period

# string = input()
# n = len(string)
# for i in range(1, n + 1):
#     period = string[:i]
#     le = n - i
#     for j in range(1, le // i + 1):
#         for k in range(i):
#             if period[k] != string[j*i + k]:
#                 break
#         else:
#             continue
#         break
#     else:
#         left_le = le % i
#         if left_le == 0 or period[:left_le] == string[-left_le:]:
#             print(period)
#             break
#
#
string = input()
n = len(string)
for le in range(1, n + 1):
    i = j = 0
    while j < n:
        if string[i] != string[j]:
            break
        i += 1
        i %= le
        j += 1
    else:
        print(string[:le])
        break

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: TIME LIMIT EXCEEDED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: TIME LIMIT EXCEEDED

Test 16

Verdict: TIME LIMIT EXCEEDED

Test 17

Verdict: TIME LIMIT EXCEEDED

Test 18

Verdict: TIME LIMIT EXCEEDED

Test 19

Verdict: TIME LIMIT EXCEEDED

Test 20

Verdict: TIME LIMIT EXCEEDED

Test 21

Verdict: TIME LIMIT EXCEEDED