#include<stdio.h>
#include<stdlib.h>
#include<ctybe.h>

int main() {
    int arr[1000], n = 0;
    char s[100];
    
    while (scanf("%s", s) == 1) {
        if(s[0] == '-' && s[1] == '1' && s[2] == '\0') break;
        
        char *p = s;
        if (*p == 's') p++;
        if (*p == '\0') { printf("Invalid input\n"); return 0; }
        while (*p) {
            if (!isdigit(*p)) { printf("Invalid input\n"); return 0; }
            p++
        }
        
        arr[n++] = atoi(s);
    }
        
        for (int i = 0; i < n /2; i++) {
            if (arr[i] != arr[n - 1 - i]){
                printf("No\n");
                return 0;
            }
        }
        printf("Yes\n");
        return 0;
 }