Lost card

n, *cards = map(int, input().split()) total_sum = sum(cards) expected_sum = n * (n + 1) // 2 missing_card = expected_sum - totalsum print(missingcard)

include <bits/stdc++.h>

using namespace std; int main () { int k=0,n,a,d; cin>>n; d=n-1; for (int i=1;i<=n;i++) { k=k+i; } while (d--) { cin>>a; k=k-a; } cout<<k; }