#include<iostream>
#include<string>
int main(){
long long int a;
  std::string str;
  int count=1;
  long long int i=26;
  long long int k;
  long long int sub=0;
  std::cin>>a;
  //a=0;
 // long long int b=0;
  //  b++;
    //a=b;
    i=26;
    sub=0;
  while(a>i+sub){
    sub+=i;
    i*=26;
    count++;
  }
   // str.erase(str.begin(),str.end());
  //std::cout<<count<<std::endl;
  //std::cout<<i<<std::endl;
  
  k=i/26;
  //std::cout<<k<<std::endl;
  while(k>1){
    a-=k;
    k/=26;
  }
 // std::cout<<a<<std::endl;
  //std::cout<<i<<std::endl;
  for(long long int j=i/26;count>1;j/=26){
    count--;
    //std::cout<<"j:"<<j<<std::endl;
    //std::cout<<"begin a"<<a<<std::endl;
    if(a==0){
      str+="z";
      std::cout<<a<<std::endl;
      continue;
      
    }
    if(a/j==0||(a/j==1&&a%j==0)){
      str+="a";
    }/*
    if(a/j==0&&a%j==0){
      str+="b";
    }
    if(a/j==0&&a%j==3){
      str+="c";
    }
    if(a/j==0&&a%j==4){
      str+="d";
    }
    if(a/j==0&&a%j==5){
      str+="e";
    }
    if(a/j==0&&a%j==6){
      str+="f";
    }
    if(a/j==0&&a%j==7){
      str+="g";
    }
    if(a/j==0&&a%j==8){
      str+="h";
    }
    if(a/j==0&&a%j==9){
      str+="i";
    }
    if(a/j==0&&a%j==10){
      str+="j";
    }
    if(a/j==0&&a%j==11){
      str+="k";
    }
    if(a/j==0&&a%j==12){
      str+="l";
    }
    if(a/j==0&&a%j==13){
      str+="m";
    }
    if(a/j==0&&a%j==14){
      str+="n";
    }
    if(a/j==0&&a%j==15){
      str+="o";
    }
    if(a/j==0&&a%j==16){
      str+="p";
    }
    if(a/j==0&&a%j==17){
      str+="q";
    }
    if(a/j==0&&a%j==18){
      str+="r";
    }
    if(a/j==0&&a%j==19){
      str+="s";
    }
    if(a/j==0&&a%j==20){
      str+="t";
    }
    if(a/j==0&&a%j==21){
      str+="u";
    }
    if(a/j==0&&a%j==22){
      str+="v";
    }
    if(a/j==0&&a%j==23){
      str+="w";
    }
    if(a/j==0&&a%j==24){
      str+="x";
    }
    if(a/j==0&&a%j==25){
      str+="y";
    }
    if(a/j==0&&a%j==26){
      str+="z";
    }*/
    if((a/j==1&&a%j!=0)||(a/j==2&&a%j==0)){
      a=a-j*1;
      str+="b";
    }
    if((a/j==2&&a%j!=0)||(a/j==3&&a%j==0)){
      a=a-j*2;
      str+="c";
    }
    if((a/j==3&&a%j!=0)||(a/j==4&&a%j==0)){
      a=a-j*3;
      str+="d";
    }
    if((a/j==4&&a%j!=0)||(a/j==5&&a%j==0)){
      a=a-j*4;
      str+="e";
    }
    if((a/j==5&&a%j!=0)||(a/j==6&&a%j==0)){
      a=a-j*5;
      str+="f";
    }
    if((a/j==6&&a%j!=0)||(a/j==7&&a%j==0)){
      a=a-j*6;
      str+="g";
    }
    if((a/j==7&&a%j!=0)||(a/j==8&&a%j==0)){
      a=a-j*7;
      str+="h";
    }
    if((a/j==8&&a%j!=0)||(a/j==9&&a%j==0)){
      a=a-j*8;
      str+="i";
    }
    if((a/j==9&&a%j!=0)||(a/j==10&&a%j==0)){
      a=a-j*9;
      str+="j";
    }
    if((a/j==10&&a%j!=0)||(a/j==11&&a%j==0)){
      a=a-j*10;
      str+="k";
    }
    if((a/j==11&&a%j!=0)||(a/j==12&&a%j==0)){
      
      a=a-j*11;
      str+="l";
    }
    if((a/j==12&&a%j!=0)||(a/j==13&&a%j==0)){
      a=a-j*12;
      str+="m";
    }
    if((a/j==13&&a%j!=0)||(a/j==14&&a%j==0)){
      a=a-j*13;
      str+="n";
    }
    if((a/j==14&&a%j!=0)||(a/j==15&&a%j==0)){
      a=a-j*14;
      str+="o";
    }
    if((a/j==15&&a%j!=0)||(a/j==16&&a%j==0)){
      a=a-j*15;
      str+="p";
    }
    if((a/j==16&&a%j!=0)||(a/j==17&&a%j==0)){
      a=a-j*16;
      str+="q";
    }
    if((a/j==17&&a%j!=0)||(a/j==18&&a%j==0)){
      a=a-j*17;
      str+="r";
    }
    if((a/j==18&&a%j!=0)||(a/j==19&&a%j==0)){
      a=a-j*18;
      str+="s";
    }
    if((a/j==19&&a%j!=0)||(a/j==20&&a%j==0)){
      a=a-j*19;
      str+="t";
    }
    if((a/j==20&&a%j!=0)||(a/j==21&&a%j==0)){
      a=a-j*20;
      str+="u";
    }
    if((a/j==21&&a%j!=0)||(a/j==22&&a%j==0)){
      a=a-j*21;
      str+="v";
    }
    if((a/j==22&&a%j!=0)||(a/j==23&&a%j==0)){
      a=a-j*22;
      str+="w";
    }
    if((a/j==23&&a%j!=0)||(a/j==24&&a%j==0)){
      a=a-j*23;
      str+="x";
    }
    if((a/j==24&&a%j!=0)||(a/j==25&&a%j==0)){
      a=a-j*24;
      str+="y";
    }
    if((a/j==25&&a%j!=0)||(a/j==26&&a%j==0)){
      a=a-j*25;
      str+="z";
    }
    if(a/j==26){
      a=a-j*26;
      str+="z";
    }
    //std::cout<<a<<std::endl;
   // std::cout<<"str:"<<str<<std::endl;
  }
    //std::cout<<a<<std::endl;
  //std::cout<<"str:"<<str<<std::endl;
  if(i>26)i=i/26;
  i=26;
  //std::cout<<"i:"<<i<<std::endl;
    if(a%i==1)str+="a";
    if(a%i==2)str+="b";
    if(a%i==3)str+="c";
    if(a%i==4)str+="d";
    if(a%i==5)str+="e";
    if(a%i==6)str+="f";
    if(a%i==7)str+="g";
    if(a%i==8)str+="h";
    if(a%i==9)str+="i";
    if(a%i==10)str+="j";
    if(a%i==11)str+="k";
    if(a%i==12)str+="l";
    if(a%i==13)str+="m";
    if(a%i==14)str+="n";
    if(a%i==15)str+="o";
    if(a%i==16)str+="p";
    if(a%i==17)str+="q";
    if(a%i==18)str+="r";
    if(a%i==19)str+="s";
    if(a%i==20)str+="t";
    if(a%i==21)str+="u";
    if(a%i==22)str+="v";
    if(a%i==23)str+="w";
    if(a%i==24)str+="x";
    if(a%i==25)str+="y";
    if(a%i==0)str+="z";
  std::cout<<str<<std::endl;
  return 0;
}

Measured memory_bytes: 3604