#include <iostream>
#include <cmath>
unsigned int remove_first_digit(unsigned int num) {
int total = (int)log10(num); // total - 1 = 6
int first_digit = num / pow(10, (total));
return num - first_digit * pow(10, (total));
}
int main(void) {
int n = 8405796;
n = remove_first_digit(n);
std::cout << n;
}
/*
run:
405796
*/