http://benji3up2kxewkqfcq7buxk2xd6zwy3zggnurkrm3l4cvwy2iipvyyad.onion/mirrors/gmpdoc/Formatted-Input-Functions.html
The vscanf forms take an argument pointer, see Variadic Functions in The GNU C Library Reference Manual , or ‘ man 3
va_start ’. It should be emphasised that if a format string is invalid, or the arguments
don’t match what the format specifies, then the behaviour of any of these
functions will be unpredictable.