(function(){ var line,len,maxStr; while(line = read_line()){ len = line.length; for(var i=0;i<len;i++){ var letter = new RegExp(/[a-z]|[A-Z]+/,"g"); if(line[i].match(letter) !== "null") { var reg = new RegExp(line[i],"g"); var num = line.match(reg).length; if(num>=3){ maxStr=line[i]; break;
                }
            }
        } print(maxStr);
    }
})();