const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    // Write your code here
    let params = []
    while(line = await readline()){
        let tokens = line.split(' ');
        // let a = parseInt(tokens[0]);
        // let b = parseInt(tokens[1]);
        // console.log(a + b);
        params.push(tokens)
    }
    // console.log(params)
    let str = params[0][0]
    let matches = str.matchAll(/[0-9]+/g)
    let maxStr = ""
    for(match of matches){
        // console.log(match)
        let str = match[0]
        if(str.length > maxStr.length){
            maxStr = str;
        }
    }
    console.log(maxStr)
}()