#include<bits/stdc++.h>
#define int long long
using namespace std;

const int N = 1e5 + 5;

int n,k,p;
int a[N];

signed main()
{
    freopen("defeat.in","r",stdin);
    freopen("defeat.out","w",stdout);
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin>>n>>k>>p;
    for(int i = 1;i <= n;i++) cin>>a[i];
    
    int ans = 0,val = 0;
    for(int i = 1;i <= n;i++){
        ans += abs(a[i] + val - k);
        val += (k - a[i] - val);
    }
    cout<<ans<<'\n';
    
    return 0;
}