#include<iostream>
using namespace std;
int main(){
    int n;
    cin >> n;
    cout << n/100 + 10*(n/10%10) + 100*(n%10);
    return 0;
}

#include<iostream>
using namespace std;
int main( )
{
int n,x,y=0;
cin>>n;
for(x=n;x!=0;x=x/10)
{
y=y*10+x%10;
}
cout<<y<<endl;
return 0;
}
最简便

#include<bits/stdc++.h>
using namespace std;
int main()
{
int a,b,c,d;
cin>>a;
b=a%10;
c=(a/10)%10;
d=a/100;
cout<<b*100+c*10+d;
return 0;
}

#include<iostream>
#include<cmath>
using namespace std;
int main( )
{
int a,s,d,f;
cin>>a;
s=a/100;
d=a%100/10;
f=a%10;
cout<<100*f+10*d+s<<endl;
return 0;
}

#include<iostream>
#include<cmath>
using namespace std;
int main()
{
int n;
int a,b,c;
cin>>n;
a=n/100;
b=n%100/10;
c=n%10;
cout<<c<<b<<a<<endl;
return 0;
}