#include<iostream> #include<cstring> using namespace std; int main(){ char a[100]; int m=-1,i=0; cin.getline(a,100); while(a[i]!='.'){ i++; if(a[i]-'0'>m) m=a[i]-'0'; } while(i<strlen(a)){ if(a[i]-'0'>m) m=a[i]-'0'; i++; } cout<<m; return 0; }