红了最后一个测试点，还100

123456789101112131415161718192021#include<bits/stdc++.h>
using namespace std;
string s1,s2;
int main()
{
    cin>>s1;
    if(s1[0]=='-')
    {
        cout<<"-";
        for(int i=s1.length()-1,j=0;i>=1;i--,j++) s2=s2+s1[i];
        if(s2[0]=='0') s2.erase(0,s2.find_first_not_of('0'));
        cout<<s2;
    }
    else
    {
        for(int i=s1.length()-1,j=0;i>=0;i--,j++) s2=s2+s1[i];
        if(s2[0]=='0')s2.erase(0,s2.find_first_not_of('0'));
        cout<<s2;
    }
    return 0;
}
//红色的100