#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() using namespace std; int main(){ int a,b,c,d,e; cin>>a; b=a%10; c=a/10%10; d=a/100%10; e=a/1000; cout<<d*1000+e*100+b*10+c; return 0; }