#include <stdio.h>
#include <ctype.h>
int fromHex(char c) {
    c = toupper(c);
    if (c >= '0' && c <= '9') {
        return c-'0';
    } else {
        return c-'A'+10;
    }
}
char toHexDigit(int n) {
    return n < 10 ? '0'+n : 'A'+n-10;
}
int main(void) {
char myNum[] = "002A05";
myNum[1] = toHexDigit(fromHex(myNum[1]) | 2);
printf("%s\n", myNum);
	return 0;
}