1 #include<bits/stdc++.h> 2 using namespace std; 3 4 string btox(string b){ 5 if(b=="0000") return "0"; 6 if(b=="0001") return "1"; 7 if(b=="0010") return "2"; 8 if(b=="0011") return "3"; 9 if(b=="0100") return "4"; 10 if(b=="0101") return "5"; 11 if(b=="0110") return "6"; 12 if(b=="0111") return "7"; 13 if(b=="1000") return "8"; 14 if(b=="1001") return "9"; 15 if(b=="1010") return "A"; 16 if(b=="1011") return "B"; 17 if(b=="1100") return "C"; 18 if(b=="1101") return "D"; 19 if(b=="1110") return "E"; 20 if(b=="1111") return "F"; 21 } 22 23 int main() { 24 long long n; 25 cin>>n; 26 if(n==0){ 27 cout<<0<<endl; 28 return 0; 29 } 30 string a=""; 31 32 while(n){ 33 a+=('0'+n%2); 34 n/=2; 35 } 36 reverse(a.begin(), a.end()); 37 38 if(a.length()%4==1){ 39 a = "000"+a; 40 }else if(a.length()%4==2){ 41 a = "00" + a; 42 }else if(a.length()%4==3){ 43 a = "0" + a; 44 } 45 string s=""; 46 for(int i=0; i<a.length(); i+=4){ 47 s+=btox(a.substr(i,4)); 48 } 49 cout<<s<<endl; 50 51 52 }