문제
풀이
#include <iostream>
#include <vector>
using namespace std;
void solve(void) {
int n, k; cin >> n >> k;
vector<bool> v(n+1, false);
while (k--) {
int d; cin >> d;
v[d] = true;
}
int ans = 0;
bool flag = false;
for (int i=1; i<=n; i++) {
flag = (i == 1 || v[i] || !flag);
if (flag) ans++;
}
cout << ans;
}
int main(void) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}