#include "cstdio"
#include "algorithm"
#include "cstring"
#include "cmath"
using namespace std;
char s[500];
int main()
{
    int ans=0,maxn;
    while (scanf("%s",s)==1){
        int n=strlen(s);
        ans=s[0]-‘0‘;
        maxn=ans;
        for(int i=1;i<n;i++){
            if(s[i]>s[i-1]){
                ans=ans*10+s[i]-‘0‘;
            }
            else {
                maxn=max(ans,maxn);
                ans=s[i]-‘0‘;
                maxn=max(ans,maxn);
            }
        }
        printf("%d\n",maxn);
    }
    return 0;
}