#include #define rep(i,n) for(long long int (i)=0;(i)<(int)(n);(i)++) #define rrep(i,a,b) for(long long int i=(a);i<(b);i++) #define rrrep(i,a,b) for(long long int i=(a);i>=(b);i--) #define all(v) (v).begin(), (v).end() #define pb(q) push_back(q) #define Size(n) (n).size() #define Cout(x) cout<<(x)<>s; string co; rrep(i,0,Size(s)/2)co+=s[i]; //Cout(co); rrep(i,Size(s)/2,Size(s)){ //Cout(s[i]); if(co[cnt++]!=s[i]){ Cout("NO"); return 0; } } Cout("YES"); return 0; }