#include <bits/stdc++.h>using namespace std;#define maxn 100005#define ll long longll ai[maxn],n,m,ans;inline void in(ll &now){    char Cget=getchar();now=0;    while(Cget>‘9‘||Cget<‘0‘)Cget=getchar();    while(Cget>=‘0‘&&Cget<=‘9‘)    {        now=now*10+Cget-‘0‘;        Cget=getchar();    }}int main(){    in(n),in(m);    for(ll i=1;i<=n;i++)    {        in(ai[i]);        if(ai[i]+ai[i-1]>m)        {            ans+=ai[i]+ai[i-1]-m;            ai[i]-=ai[i]+ai[i-1]-m;        }    }    cout<<ans;    return 0;}