#import <Foundation/Foundation.h>
#include <stdio.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int n;
        scanf("%d", &n);
        NSString *result = @"Yes";
        NSMutableArray *arr = [NSMutableArray array];
        NSString *f, *b;
        for (int i=0;i<n;i++) {
            NSData *stdinData = [[NSFileHandle fileHandleWithStandardInput] availableData];
            NSString *raw = [[NSString alloc] initWithData:stdinData encoding:NSUTF8StringEncoding];
            NSString *s = [raw substringToIndex:[raw length]-1];
            if ([arr containsObject:s]) {
                result = @"No";
            }
            [arr addObject:s];
            
            if (!i){
                f = [s substringToIndex:1];
                b = [s substringFromIndex:[s length]-1];
            }
            else {
                if ([s substringToIndex:1] != b){
                    result = @"No";
                }
                f = [s substringToIndex:1];
                b = [s substringFromIndex:[s length]-1];
            }
        }
        
        NSFileHandle *fileHandle = [NSFileHandle fileHandleWithStandardOutput];
        [fileHandle writeData:[result dataUsingEncoding:NSUTF8StringEncoding]];
        [fileHandle writeData:[@"\n" dataUsingEncoding:NSUTF8StringEncoding]];
        [fileHandle closeFile];
    }
    return 0;
}
