Python 3.11+sysfunction

sys.set_int_max_str_digits()

interpreter

Changes the digit limit for converting int to str and back (4300 by default); 0 removes it. Needed in tasks with very long numbers.

Syntax

sys.set_int_max_str_digits(maxdigits)

When a solution prints a huge factorial or Fibonacci number, put sys.set_int_max_str_digits(0) first — otherwise print or int(input()) raises ValueError. Values 1 to 639 are rejected: use 0 or at least 640. Older branches have the limit too (since 3.10.7, 3.9.14, 3.8.14 as a security fix), and it can be set from outside with PYTHONINTMAXSTRDIGITS or -X int_max_str_digits.

Examples

import math, sys
sys.set_int_max_str_digits(0)
s = str(math.factorial(2000))
print(len(s))  # → 5736

# Python 3.14+
import sys
try:
    sys.set_int_max_str_digits(100)
except ValueError as e:
    print(e)  # → maxdigits must be >= 640 or 0 for unlimited

import sys
sys.set_int_max_str_digits(5000)
print(len(str(10 ** 4999)))  # → 5000

See also

Common errors

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