#include <iostream>
#include <string.h>
using namespace std;

int main()
{
    char s[256],*p,sep[]=" ",nr[101];
    cin.get(s,256); nr[0]='\0';
    p=strtok(s,sep);
    while(p!=NULL)
    {
        if(p[0]>='0'&&p[0]<='9')
            if(nr[0]=='\0')
                strcpy(nr,p);
            else
                if(strcmp(nr,p)==-1)
                    strcpy(nr,p);
        p=strtok(NULL,sep);
    }
    if(nr[0]=='\0')
        cout<<"nu exista";
        else cout<<nr;
    return 0;
}