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

typedef struct {
    size_t a;
    size_t b;
} Pair;

bool isBirthdayPair(const Pair *p1, const Pair *p2) {
    return (p1->a == p2->a && p1->b == p2->b);
}

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

    for (size_t i = 0; i < n; i++)
    {
        scanf("%zu%zu", &pairs[i].a, &pairs[i].b);
        //printf_s("%d %d\n", pairs[i].a, pairs[i].b);
        if(i != 0) {
            for (size_t j = 0; j < i; j++)
            {
                if (isBirthdayPair(&pairs[i], &pairs[j])) {
                    BirthdayFlag = true;
                    break;
                }
            }
            
        }

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