#include <bits/stdc++.h>
using namespace std;
int main() {
    int x = 255;      // FF
    vector<int> path; // 动态数组
    while (x) {
        int a = x % 16;
        path.push_back(a);
        x /= 16;
    }
    for (int i = path.size() - 1; i >= 0; i--) {
        if (path[i] < 10)
            cout << path[i];
        else
            printf("%c", 'A' + (path[i] - 10));
    }
    return 0;
}