C++ ( ko dùng abs, math, cmath,if,for,..) GIÚP VS HỨA RATE5* & CTRLHN

\begin{array}{c} \color{#db1616}{\texttt{#Khoadang09}} \end{array}

#include <bits/stdc++.h>
using namespace std;
int main(){
    string s; cin >> s;
    if (s[0]=='-') for (int i=1;i<s.length();i++) cout << s[i];
    else cout << s ;
}