Go: package main

import (
	"bufio"
	"os"
	"strconv"
	"fmt"
)

var scanner= bufio.NewScanner(os.Stdin)

func main() {
	for scanner.Scan() {
		n, _ := strconv.Atoi(scanner.Text())
		if n%39 == 0 {
			fmt.Println(fmt.Sprintf("3C%02d", 39))
			continue
		}
		fmt.Println(fmt.Sprintf("3C%02d", n%39))
	}
}

C++: 
#include <bits/stdc++.h>

class kin{
public:
	inline void open(FILE *,int);
	inline void close(void);
	inline void scan(void);
	inline kin &operator>(char &);
	inline kin &operator>(int &);
	inline kin &operator>(long long &);
	inline kin &operator>(double &);
	inline kin &operator>(long double &);
	inline kin &operator>(char *);
	template <class T> inline void get(T *,int);
private:
	FILE *fp;
	char *buf;
	int siz;
	int idx;
}in;

class kout{
public:
	inline void open(FILE *,int);
	inline void close(void);
	inline void print(void);
	inline kout &operator<(char);
	inline kout &operator<(int);
	inline kout &operator<(long long);
	inline kout &operator<(double);
	inline kout &operator<(long double);
	inline kout &operator<(const char *);
	template <class T> inline void put(T *,int,char,char);
private:
	FILE *fp;
	char *buf;
	int siz;
	int idx;
}out;

int main(int argc,char **argv){
	in.open(stdin,512);
	out.open(stdout,512);
	in.scan();
	while(1){
		int a;
		in>a;
		if(!a) break;
		out<"3C";
		a%=39;
		if(!a) a=39;
		if(a<=9) out<'0';
		out<a<'\n';
	}
	out.print();
	in.close();
	out.close();
	return 0;
}

inline void kin::open(FILE *fpa,int siza){
	fp=fpa;
	buf=new char[siza];
	siz=siza;
	idx=0;
	return;
}
inline void kin::close(void){
	fp=nullptr;
	delete[] buf;
	buf=nullptr;
	siz=0;
	idx=0;
	return;
}
inline void kin::scan(void){
	int readsiz=(int)std::fread((void *)buf,(std::size_t)1,(std::size_t)siz,fp);
	if(readsiz!=siz) buf[readsiz]='\x00';
	idx=0;
	return;
}
inline kin &kin::operator>(char &var){
	if(!buf[idx]){
		var='\x00';
		return *this;
	}
	var=buf[idx];
	if(++idx==siz) scan();
	if(++idx==siz) scan();
	return *this;
}
inline kin &kin::operator>(int &var){
	if(!buf[idx]){
		var=0;
		return *this;
	}
	int sign=-1;
	if(buf[idx]=='-'){
		sign=1;
		if(++idx==siz) scan();
	}
	var=0;
	while(buf[idx]>='0'){
		var=var*10-(int)(buf[idx]-'0');
		if(++idx==siz) scan();
	}
	var*=sign;
	if(++idx==siz) scan();
	return *this;
}
inline kin &kin::operator>(long long &var){
	if(!buf[idx]){
		var=0LL;
		return *this;
	}
	long long sign=-1LL;
	if(buf[idx]=='-'){
		sign=1LL;
		if(++idx==siz) scan();
	}
	var=0LL;
	while(buf[idx]>='0'){
		var=var*10LL-(long long)(buf[idx]-'0');
		if(++idx==siz) scan();
	}
	var*=sign;
	if(++idx==siz) scan();
	return *this;
}
inline kin &kin::operator>(double &var){
	if(!buf[idx]){
		var=0.0;
		return *this;
	}
	double sign=-1.0;
	if(buf[idx]=='-'){
		sign=1.0;
		if(++idx==siz) scan();
	}
	var=0.0;
	while(buf[idx]>='0'){
		var=var*10.0-(double)(buf[idx]-'0');
		if(++idx==siz) scan();
	}
	if(buf[idx]=='.'){
		if(++idx==siz) scan();
		double dig=1.0;
		while(buf[idx]>='0'){
			var-=(double)(buf[idx]-'0')*(dig/=10.0);
			if(++idx==siz) scan();
		}
	}
	var*=sign;
	if(++idx==siz) scan();
	return *this;
}
inline kin &kin::operator>(long double &var){
	if(!buf[idx]){
		var=0.0L;
		return *this;
	}
	long double sign=-1.0L;
	if(buf[idx]=='-'){
		sign=1.0L;
		if(++idx==siz) scan();
	}
	var=0.0L;
	while(buf[idx]>='0'){
		var=var*10.0L-(long double)(buf[idx]-'0');
		if(++idx==siz) scan();
	}
	if(buf[idx]=='.'){
		if(++idx==siz) scan();
		long double dig=1.0L;
		while(buf[idx]>='0'){
			var-=(long double)(buf[idx]-'0')*(dig/=10.0L);
			if(++idx==siz) scan();
		}
	}
	var*=sign;
	if(++idx==siz) scan();
	return *this;
}
inline kin &kin::operator>(char *var){
	if(!buf[idx]){
		var[0]='\x00';
		return *this;
	}
	int ptr=0;
	while(buf[idx]>='!'){
		var[ptr++]=buf[idx];
		if(++idx==siz) scan();
	}
	var[ptr]='\x00';
	if(++idx==siz) scan();
	return *this;
}
template<class T>
inline void kin::get(T *var,int num){
	for(int i=0;i<num;++i) (*this)>var[i];
	return;
}

inline void kout::open(FILE *fpa,int siza){
	fp=fpa;
	buf=new char[siza];
	siz=siza;
	idx=0;
	return;
}
inline void kout::close(void){
	fp=nullptr;
	delete[] buf;
	buf=nullptr;
	siz=0;
	idx=0;
	return;
}
inline void kout::print(void){
	std::fwrite((void *)buf,(std::size_t)1,(std::size_t)idx,fp);
	idx=0;
	return;
}
inline kout &kout::operator<(char val){
	buf[idx]=val;
	if(++idx==siz) print();
	return *this;
}
inline kout &kout::operator<(int val){
	if(val<0){
		buf[idx]='-';
		if(++idx==siz) print();
	}
	else val*=-1;
	char dig[10];
	int ptr=0;
	do{
		int tmp=val/10;
		dig[ptr++]=(char)-(val-tmp*10)+'0';
		val=tmp;
	}while(val);
	while(ptr--){
		buf[idx]=dig[ptr];
		if(++idx==siz) print();
	}
	return *this;
}
inline kout &kout::operator<(long long val){
	if(val<0LL){
		buf[idx]='-';
		if(++idx==siz) print();
	}
	else val*=-1LL;
	char dig[19];
	int ptr=0;
	do{
		long long tmp=val/10LL;
		dig[ptr++]=(char)-(val-tmp*10LL)+'0';
		val=tmp;
	}while(val);
	while(ptr--){
		buf[idx]=dig[ptr];
		if(++idx==siz) print();
	}
	return *this;
}
inline kout &kout::operator<(double val){
	if(val<0.0){
		buf[idx]='-';
		if(++idx==siz) print();
	}
	else val*=-1.0;
	double dig=1.0;
	while(val/dig<=-10.0) dig*=10.0;
	int tmp;
	while(dig>=1.0){
		buf[idx]=(char)-(tmp=(int)(val/dig))+'0';
		if(++idx==siz) print();
		val-=(double)tmp*dig;
		dig/=10.0;
	}
	buf[idx]='.';
	if(++idx==siz) print();
	for(int i=0;i<12;++i){
		buf[idx]=(char)-(tmp=(int)(val/dig))+'0';
		if(++idx==siz) print();
		val-=(double)tmp*dig;
		dig/=10.0;
	}
	return *this;
}
inline kout &kout::operator<(long double val){
	if(val<0.0L){
		buf[idx]='-';
		if(++idx==siz) print();
	}
	else val*=-1.0L;
	long double dig=1.0L;
	while(val/dig<=-10.0L) dig*=10.0L;
	int tmp;
	while(dig>=1.0L){
		buf[idx]=(char)-(tmp=(int)(val/dig))+'0';
		if(++idx==siz) print();
		val-=(long double)tmp*dig;
		dig/=10.0L;
	}
	buf[idx]='.';
	if(++idx==siz) print();
	for(int i=0;i<16;++i){
		buf[idx]=(char)-(tmp=(int)(val/dig))+'0';
		if(++idx==siz) print();
		val-=(long double)tmp*dig;
		dig/=10.0L;
	}
	return *this;
}
inline kout &kout::operator<(const char *val){
	for(int i=0;val[i];++i){
		buf[idx]=val[i];
		if(++idx==siz) print();
	}
	return *this;
}
template<class T>
inline void kout::put(T *val,int num,char spc,char end){
	--num;
	for(int i=0;i<num;++i) (*this)<val[i]<spc;
	(*this)<val[num]<end;
	return;
}

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

int main() {
  int n;
  while(cin >> n) {
    printf("3C%02d\n", (n+38)%39 + 1);
  }
  return 0;
}

C++: #include <iostream>
using namespace std;

int main(void)
{
	int n;
	while (scanf("%d", &n) != EOF){
		printf("3C%02d\n", n%39==0?39:n%39);
	}
	return 0;
}

C++: #include<iostream>
#include<cstdio>

using namespace std;

int main()
{
	int n;
	
	for(;cin >> n;)
	{
		int ans=n%39;
		if(n%39==0)
			ans=39;
		printf("3C%02d\n",ans);
	}
}

C++: #include<iostream>
using namespace std;

int main(void){
	int q;
	while(~scanf("%d",&q)){
		q=q%39;
		if(q==0)q=39;
		printf("3C%02d\n",q);
	}
    return 0;
}

C++: #include<iostream>
#include<cstdio>
using namespace std;
int main(){
    int n;
    while(cin>>n){
        int ans=n%39;
        if(!ans)ans=39;
        printf("3C%2.2d\n",ans);
    }
    return 0;
}

C++: #include <stdio.h>

int main(void){
		
	int a;
		
	while(1){
		if(scanf("%d", &a) == EOF )
				break;
			
		a = a % 39;
		if(a == 0)	a = 39;
		printf("3C%02d\n", a);
	}
		
	return 0;
}

C++: #include <iostream>
 
using namespace std;
 
int main() {
    int candy = 0;
       
    while (true){
    cin >> candy;
    if (candy == -1) {
        break;
    }
     
    cout << candy % 39 << endl;
     
    }
}

C++: #include<stdio.h>
int main(void)
{
    int a;
	while(scanf("%d",&a)!=EOF){
		a=a%39;
		if(a==0){
			printf("3C39\n");
		}
		else{ 
			printf("3C%02d\n",a);
		}
	}
	return 0;
}