#include <iostream>
int max_number(int value, int last_max = 0) {
if (!value || last_max == 9) return last_max;
last_max = std::max(last_max, value % 10);
return max_number(value / 10, last_max);
}
int main() {
int value = 78421;
std::cout << "max number is: " << max_number(value);
}
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