Language: C++

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)


int main() {
  long long N;
  cin >> N;
  
  long long x=N;
  int y;
  vector<int> vec;
  
  for (int i = 0; i < 100; i++){
    x = x/26;
    y = N%26;
    
    vec.at(i) =y;
    
    if(x==0){
      break;
    }
  }
  
  reverse(vec.begin(), vec.end());
  
  for(int i = 0; i<100; i++){
    if(vec.at(i) ==1){
      cout << "a" <<;
    }
    else if(vec.at(i) ==2){
      cout << "b" <<;
    }
    else if(vec.at(i) ==3){
      cout << "c" <<;
    }
    else if(vec.at(i) ==4){
      cout << "d" <<;
    }
    else if(vec.at(i) ==5){
      cout << "e" <<;
    }
    else if(vec.at(i) ==6){
      cout << "f" <<;
    }
    else if(vec.at(i) ==7){
      cout << "g" <<;
    }
    else if(vec.at(i) ==8){
      cout << "h" <<;
    }
    else if(vec.at(i) ==9){
      cout << "i" <<;
    }
    else if(vec.at(i) ==10){
      cout << "j" <<;
    }
    else if(vec.at(i) ==11){
      cout << "k" <<;
    }
    else if(vec.at(i) ==12){
      cout << "l" <<;
    }
    else if(vec.at(i) ==13){
      cout << "m" <<;
    }
    else if(vec.at(i) ==14){
      cout << "n" <<;
    }
    else if(vec.at(i) ==15){
      cout << "o" <<;
    }
    else if(vec.at(i) ==16){
      cout << "p" <<;
    }
    else if(vec.at(i) ==17){
      cout << "q" <<;
    }
    else if(vec.at(i) ==18){
      cout << "r" <<;
    }
    else if(vec.at(i) ==19){
      cout << "s" <<;
    }
    else if(vec.at(i) ==20){
      cout << "t" <<;
    }
    else if(vec.at(i) ==21){
      cout << "u" <<;
    }
    else if(vec.at(i) ==22){
      cout << "v" <<;
    }
    else if(vec.at(i) ==23){
      cout << "w" <<;
    }
    else if(vec.at(i) ==24){
      cout << "x" <<;
    }
    else if(vec.at(i) ==25){
      cout << "y" <<;
    }
    else if(vec.at(i) ==26){
      cout << "z" <<;
    }
    else{
      break;
    }
  }
}


Compiler output:
a.cc: In function 'int main()':
a.cc:29:21: error: expected primary-expression before ';' token
   29 |       cout << "a" <<;
      |                     ^
a.cc:32:21: error: expected primary-expression before ';' token
   32 |       cout << "b" <<;
      |                     ^
a.cc:35:21: error: expected primary-expression before ';' token
   35 |       cout << "c" <<;
      |                     ^
a.cc:38:21: error: expected primary-expression before ';' token
   38 |       cout << "d" <<;
      |                     ^
a.cc:41:21: error: expected primary-expression before ';' token
   41 |       cout << "e" <<;
      |                     ^
a.cc:44:21: error: expected primary-expression before ';' token
   44 |       cout << "f" <<;
      |                     ^
a.cc:47:21: error: expected primary-expression before ';' token
   47 |       cout << "g" <<;
      |                     ^
a.cc:50:21: error: expected primary-expression before ';' token
   50 |       cout << "h" <<;
      |                     ^
a.cc:53:21: error: expected primary-expression before ';' token
   53 |       cout << "i" <<;
      |                     ^
a.cc:56:21: error: expected primary-expression before ';' token
   56 |       cout << "j" <<;
      |                     ^
a.cc:59:21: error: expected primary-expression before ';' token
   59 |       cout << "k" <<;
      |                     ^
a.cc:62:21: error: expected primary-expression before ';' token
   62 |       cout << "l" <<;
      |                     ^
a.cc:65:21: error: expected primary-expression before ';' token
   65 |       cout << "m" <<;
      |                     ^
a.cc:68:21: error: expected primary-expression before ';' token
   68 |       cout << "n" <<;
      |                     ^
a.cc:71:21: error: expected primary-expression before ';' token
   71 |       cout << "o" <<;
      |                     ^
a.cc:74:21: error: expected primary-expression before ';' token
   74 |       cout << "p" <<;
      |                     ^
a.cc:77:21: error: expected primary-expression before ';' token
   77 |       cout << "q" <<;
      |                     ^
a.cc:80:21: error: expected primary-expression before ';' token
   80 |       cout << "r" <<;
      |                     ^
a.cc:83:21: error: expected primary-expression before ';' token
   83 |       cout << "s" <<;
      |                     ^
a.cc:86:21: error: expected primary-expression before ';' token
   86 |       cout << "t" <<;
      |                     ^
a.cc:89:21: error: expected primary-expression before ';' token
   89 |       cout << "u" <<;
      |                     ^
a.cc:92:21: error: expected primary-expression before ';' token
   92 |       cout << "v" <<;
      |                     ^
a.cc:95:21: error: expected primary-expression before ';' token
   95 |       cout << "w" <<;
      |                     ^
a.cc:98:21: error: expected primary-expression before ';' token
   98 |       cout << "x" <<;
      |                     ^
a.cc:101:21: error: expected primary-expression before ';' token
  101 |       cout << "y" <<;
      |                     ^
a.cc:104:21: error: expected primary-expression before ';' token
  104 |       cout << "z" <<;
      |                     ^