# include<iostream> using namespace std; int main(){ char a[1000]; int l = 0, _max = 0; cin>>a; while(a[l]!='\0')l++; for(int i = 0; i < l; i++)if(a[i]!='.'&&(int)(a[i])-48>_max)_max=a[i]-48; cout<<_max; return 0; }