#include <iostream>
using namespace std;
int main() {
string str;
cin >> str;
//双指针
int left = 0;
int right = 0;
string max_len_str = "";
string temp = "";
int max_len = 0;
for (int i = 0; i < str.size(); i ++){
if (str[i] >= '0' && str[i] <= '9'){
left = i;
right = i;
while (str[right] >= '0' && str[right] <= '9' && right < str.size()) {
temp += str[right];
right ++;
}
i = right;
if (max_len < right - left){
max_len_str = temp;
max_len = right - left;
}
} else {
temp = "";
continue;
}
}
cout << max_len_str << endl;
return 0;
}
// 64 位输出请用 printf("%lld")