#include <stdio.h>
#include <stdbool.h>
 
#define MAX_IDENTIFICATION 400001
#define MAX_N 200001
 
// Function to select the maximum number of warriors
int maxWarriors(int warriors[][2], int N) {
    bool selectedNumbers[MAX_IDENTIFICATION] = {false}; // Array to keep track of selected identification numbers
 
    for (int i = 0; i < N; ++i) {
        // Add both identification numbers to the array
        selectedNumbers[warriors[i][0]] = true;
        selectedNumbers[warriors[i][1]] = true;
    }
 
    int count = 0;
    for (int i = 1; i < MAX_IDENTIFICATION; ++i) {
        if (selectedNumbers[i]) {
            count++;
        }
    }
 
    return count;
}
 
int main() {
    int N;
    scanf("%d", &N);
    int warriors[MAX_N][2];
 
    for (int i = 0; i < N; ++i) {
        scanf("%d %d", &warriors[i][0], &warriors[i][1]);
    }
 
    int result = maxWarriors(warriors, N);
    printf("%d\n", result);
 
    return 0;
}