function LongestWord(sen) {
    //console.log('runcode');
    let senArr = sen.split('');
    senArr.push('$');
    let longestWordCount = 0;
    let max = 0;
    let breakWords = {};
    let breakWord = '';
    let nonLetterCount = 0;
    senArr.forEach(ch => {
      if (isLetter(ch)){
          longestWordCount+= 1;
          breakWord=breakWord+ch;
      } else {
          nonLetterCount+=1;
          // Non alphabet word handle
          if (!breakWords[longestWordCount]){
            breakWords[longestWordCount]=breakWord;
          }
          // set max
          if (longestWordCount>max){
              max = longestWordCount;
          }
          longestWordCount = 0;
          breakWord = '';
      }
    });

    if (nonLetterCount ===0)
        return sen;
    return breakWords[max];

}

function isLetter(str) {
    var re = /^[a-zA-Z ]+$/;
    //console.log('str',str);
    //console.log('str.match',str.match(re) ? true : false)
    return str.match(re) && str !== " " ? true : false;
}

//isLetter('a');
// keep this function call here
//LongestWord(readline());