python3, 41 bytes

Result

WA

Code [DL]

while 1:int(not (int(input())*8+1)**.5%1)

stdin

01111110
00000110
01010010
01011011
00001101
00000000
11111001
01100010
01001001
11101111
10111110
00111001
01000010
10100111
00011100
11100110
00010010
10001000
10011001
11111101
10101100
01101110
00000100
00100110
00101101
00101111
10100010
11001110
10000101
10101011
00110111
11010010
01111001
00000011
10010111
11100111
00010101
01110000
00001010
01001110
00100100
11000010
00000001
00001010
01101001
01111000
10101110
00001111
10000000
00000001

stdout

stderr

Traceback (most recent call last):
  File "/volume/CODE", line 1, in <module>
    while 1:int(not (int(input())*8+1)**.5%1)
EOFError: EOF when reading a line

strace