#include <bits/stdc++.h>

/* strict input checker */

int read_int() {
	int c = getchar(), s = 0, res = 0;
	if (c == '-') s = 1, c = getchar();
	assert('0' <= c && c <= '9');
	if (s) assert(c != '0');
	res = c - '0';
	while (1) {
		c = getchar();
		if (c < '0' || c > '9') break;
		assert(res <= 200000000); // avoid overflow
		assert(res); // no leading-zero
		res = res * 10 + c - '0';
	}
	ungetc(c, stdin);
	return s ? -res : res;
}
void read_linebreak() {
	int c = getchar();
	if (c == '\r') c = getchar();
	assert(c == '\n');
}

int main() {
	int n = read_int();
	read_linebreak();
	
	assert(1 <= n && n <= 200000);
	
	std::set<int> all;
	for (int i = 0; i < n; i++) {
		int a = read_int();
		if (i < n - 1)assert(getchar() == ' ');
		else read_linebreak();
		
		assert(1 <= a && a <= n);
		assert(all.insert(a).second);
	}
	
	assert(getchar() == EOF);
	return 0;
}