Language: Java

/*input
475256
*/
import java.util.*;
import java.io.*;
import java.math.BigInteger;
 
import static java.lang.Math.*;
 
// just random try
public class cf1 implements Runnable {   
	
 
	long gcd(long a, long b) 
	{ 
	    if (a == 0) 
	        return b; 
	    return gcd(b % a, a); 
	} 
 
   long power(long x, long y, long p)
    {
       
        long res = 1;     
   
        x=x % p; 
     
        while (y > 0)
        {
            
            if((y & 1)==1)
                res = ((res%p) * (x%p))% p;
     
            y =y >> 1; 
            x =((x%p)*(x%p))%p; 
        }
        return res;
    }
   
  	
	public void run() {
		
		InputReader in = new InputReader(System.in);
		PrintWriter w = new PrintWriter(System.out);
		
		long n=in.nextLong();
		StringBuffer s=new StringBuffer("");
		while(n!=0){
			s.append((char)(97 + ((n%26)-1+26)%26));
			if(n%26==0)
				n-=1;
			n/=26;
		}

		w.println(s.reverse());
		w.close();
	}
	
	static class InputReader {
		
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
		private SpaceCharFilter filter;
		
		public InputReader(InputStream stream) {
			this.stream = stream;
		}
		
		public int read() {
			
			if (numChars==-1) 
				throw new InputMismatchException();
			
			if (curChar >= numChars) {
				
				curChar = 0;
				
				try {
					numChars = stream.read(buf);
				}
				catch (IOException e) {
					throw new InputMismatchException();
				}
				
				if(numChars <= 0)				
					return -1;
			}
			
			return buf[curChar++];
		}
		 
		public String nextLine() {
			
			BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
			String str = "";
	        
			try {
	            str = br.readLine();
	        }
	        catch (IOException e) {
	            e.printStackTrace();
	        }
			
	        return str;
		}
		
		public int nextInt() {
		
			int c = read();
			
			while(isSpaceChar(c)) 
				c = read();
			
			int sgn = 1;
			
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			
			int res = 0;
			
			do {
				if(c<'0'||c>'9') 
					throw new InputMismatchException();
				
				res *= 10;
				res += c - '0';
				c = read();
			}
			while (!isSpaceChar(c)); 
			
			return res * sgn;
		}
		
		public long nextLong() {
			
			int c = read();
			
			while (isSpaceChar(c))
				c = read();
			
			int sgn = 1;
			
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			
			long res = 0;
			
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				
				res *= 10;
				res += c - '0';
				c = read();
			}
			
			while (!isSpaceChar(c));
				return res * sgn;
		}
		
		public double nextDouble() {
			
			int c = read();
			
			while (isSpaceChar(c))
				c = read();
			
			int sgn = 1;
			
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			
			double res = 0;
			
			while (!isSpaceChar(c) && c != '.') {
				
				if (c == 'e' || c == 'E')
					return res * Math.pow(10, nextInt());
				
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				
				res *= 10;
				res += c - '0';
				c = read();
			}
			
			if (c == '.') {
				
				c = read();
				double m = 1;
				while (!isSpaceChar(c)) 
				{
					if (c == 'e' || c == 'E')
						return res * Math.pow(10, nextInt());
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					m /= 10;
					res += (c - '0') * m;
					c = read();
				}
			}
			
			return res * sgn;
		}
		
		public String readString() {
			
			int c = read();
			
			while (isSpaceChar(c))
				c = read();
			
			StringBuilder res = new StringBuilder();
			
			do {
				res.appendCodePoint(c);
				c = read();
			} 
			while (!isSpaceChar(c));
			
			return res.toString();
		}
	 
		public boolean isSpaceChar(int c) {
			
			if (filter != null)
				return filter.isSpaceChar(c);
			
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
	 
		public String next() {
			return readString();
		}
		
		public interface SpaceCharFilter {
			public boolean isSpaceChar(int ch);
		}
	
	}
 
	public static void main(String args[]) throws Exception {
		new Thread(null, new cf1(),"cf1",1<<26).start();
	}
}   

Compiler output:
Main.java:11: error: class cf1 is public, should be declared in a file named cf1.java
public class cf1 implements Runnable {   
       ^
1 error