转16进制

mp["0000"] = "0";
mp["0001"] = "1";
mp["0010"] = "2";
mp["0011"] = "3";
mp["0100"] = "4";
mp["0101"] = "5";
mp["0110"] = "6";
mp["0111"] = "7";
mp["1000"] = "8";
mp["1001"] = "9";
mp["1010"] = "A";
mp["1011"] = "B";
mp["1100"] = "C";
mp["1101"] = "D";
mp["1110"] = "E";
mp["1111"] = "F";
cin >> s;
int l = s.size();
if(l % 4){
	for(int i = 0; i < 4 - l % 4; i++){
		s = '0' + s;
	}
}
for(int i = 0; i < s.size(); i += 4){
	cout << mp[s.substr(i, 4)];
}
return 0;