const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin
});

let length;
let arr = [];
rl.on('line', (line) => {
    if (length === undefined) {
        length = Number(line);
    } else {
        if (arr.length < length) {
            arr.push(line);
        }

        if (arr.length === length) {
        }
    }
})
.on('close', () => {
    let result = 0;
    let comb = 0;

    for (let i = 0; i < arr.length; i++) {
        if (!!arr[i]) {
            comb++;
        } else {
            result = comb > result ? comb : result;
            comb = 0;
        }
    }

    process.stdout.write(result.toString());
});