#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ char a[51]={0} int a1; cin>>a; a1=strlen(a);//获取子符串的长 for(int i=0;i<a1;i+=3) cout<<a[a1]; return 0; }