#include #include #include #include #include #include #include #include #include #include using namespace std; #define FOR(i,a,b) for (int i=(a);i<(b);++i) #define ROF(i,b,a) for (int i=(b);i>(a);--i) #define REP(i,n) FOR(i,0,n) #define PER(i,n) ROF(i,n-1,-1) typedef int i32; typedef long long int i64; typedef unsigned long long int ui64; typedef float f32; typedef double f64; typedef long double f128; typedef pair Pi; constexpr int INF = 1e9 + 7; constexpr int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1}; int main() { string s; cin>>s; string ans = ""; int i = 0; while(i