#include<iostream> #include<cstdio> #include<cstring> using namespace std; char a[100],b[100]; int main(){ cin>>a; int max; max=a[0]-'0'; int len=strlen(a); for(int i=1;i<len;i++){ if(a[i]=='.'){ continue; } if(a[i]-'0'>max){ max=a[i]-'0'; } } cout<<max; return 0; }