#include <stdio.h>
#include <stdbool.h>
#include <string.h>

int main(void) {
    size_t n = 0;
    scanf("%zu", &n);
    bool BirthdayFlag = false;
    char str_array[n][12];

    for (size_t i = 0; i < n; i++) {
        size_t a, b;
        scanf("%zu%zu", &a, &b);
        snprintf(str_array[i], sizeof(str_array[i]), "{%zu,%zu}", a, b);

        for (size_t j = 0; j < i; j++) {
            if (strcmp(str_array[j], str_array[i]) == 0) {
                BirthdayFlag = true;
                break;
            }
        }
    }

    if (BirthdayFlag) {
        printf("Yes\n");
    } else {
        printf("No\n");
    }
    return 0;
}