var lines = [] var reader = require('readline').createInterface({ input: process.stdin, output: process.stdout }); reader.on('line', (line) => { lines.push(line); }); reader.on('close', () => { var num = parseInt(lines); num.sort(); var A = num[0]; var B = num[1]; var C = num[2]; var D = num[3]; if(D - C == 1 && C - B == 1 && B - A == 1){ console.log('Yes'); } else { console.log('No'); } });