#include<iostream>
#include<algorithm>
#include<cmath>
#define int long long
using namespace std;
#define rep(s,i,n) for(int i=s;i<n;i++)
#define c(n) cout<<n<<endl;
int a[214514];
signed main(){
	int n;
	cin>>n;
	int ans=0;
	rep(0,i,n){
		cin>>a[i];
		ans+=a[i];
		ans-=i+1;
	}
	c(ans)
}	
