process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
    function readNumber() {
		return Number(readLine());
	}
	
	function readNumberArray() {
		return readLine().trim().split(' ').map(Number);
	}
    
    let n = readNumber(),
        a = readNumberArray(),
        maxCount = 0;
    
    for (let i = 0; i < n; i++) {
        let baseNumber = a[i];
        let plusOneGroupLength = a.reduce((t, v, index) => {
            if (index === i) { return t; }
            if (v === baseNumber || v === baseNumber - 1) { t++; }
            return t;
        }, 0) + 1;
        
        let minusOneGroupLength = a.reduce((t, v, index) => {
            if (index === i) { return t; }
            if (v === baseNumber || v === baseNumber + 1) { t++; }
            return t;
        }, 0) + 1;
        
        maxCount = Math.max(maxCount, plusOneGroupLength, minusOneGroupLength);
    }
    
    console.log(maxCount);
}