include <bits/stdc++.h>
using namespace std;

//将一个16进制的灰阶转为一个整数，方便用来当数组的下标索引值
int toDec(char a, char b) {
	int res = 0;
	if (a >= '0' && a <= '9')
		res += (a - '0') * 16;
	else if (a >= 'A' && a <= 'F')
		res += (a - 'A' + 10) * 16;

	if (b >= '0' && b <= '9')
		res += b - '0';
	else if (b >= 'A' && b <= 'F')
		res += b - 'A' + 10;
	return res;
}

//将一个十进制的灰阶值[0,255]转化成十六进制[0,FF]
string toHex(int x) {
	char c1, c2;
	int a = x % 16; // 0 ~ 15
	int b = x / 16; //
	if (a >= 10)
		c1 = 'A' + a - 10;
	else
		c1 = '0' + a;
	if (b >= 10)
		c2 = 'A' + b - 10;
	else
		c2 =  '0' + b;

	string res;
	res.push_back(c2);
	res.push_back(c1);
	return res;
}

int main() {
	cout << toDec('A', 'B') << endl;// AB-->? 10*16+ 11 =171
	cout << toDec('1', '3') << endl;// 19
	cout << toDec('1', 'A') << endl;// 26

	cout << toHex(171) << endl; //AB
	cout << toHex(19) << endl; //13
	cout << toHex(26) << endl; //1A
	return 0;
}