You are a king and you are at war. If the enemy breaks through your frontline you lose.
Enemy can break the line only if the sum of morale of any $K$ continuous soldiers is strictly less than $M$. So, you being a motivational orator decides to boost their morale by giving a speech. On hearing it morale of a soldier multiplies by $X$ which depends on you and your speech (i.e. $X$ can be any positive value) but atmost only $K$ continuous speakers can hear your speech.
N soldiers are standing on the frontline with $A[i]$ morale. 
Determine the minimum number of speeches you need to give.
-----Input:-----
The first line contains three space seperated integers $N,K,M$.
The next line contains $N$ space integers, ith of which denotes the morale of $ith$ soldier.
-----Output:-----
Output the minimum number of speeches required. In case if it is impossible to achieve, print $-1$.
-----Constraints:-----
$1 \leq N,M \leq 10^5$
$1 \leq k \leq N$
$0 \leq Ai \leq 10^5$ 
-----Sample Input:-----
6 2 5
1 1 1 1 1 1
-----Sample Output:-----
2
-----Explanation:-----
We multiply 2nd ,3rd  and 5th,6th by 5. Resulting array will be 1 5 5 1 5 5.
N,K,M=list(map(int,input().split()))
A=list(map(int,input().split()))
tt=0
i=0
while(i<N):
    k1=-1
    j=0
    c=0
    while(j<K and i<N):
        if (A[i]!=0):
            k1=i
        c=c+A[i]
        i=i+1
        j=j+1
        
    while(c>=M and i<N):
        if (A[i]!=0):
            k1=i
        c=c+A[i]-A[i-K]
        i=i+1

    if (k1<0):
        tt=-1
        break

    elif (c<M and j==K):
        tt=tt+1
        i=k1+K
    #print(i,c)
    
print(tt)
        
    
    

N,K,M=list(map(int,input().split()))
A=list(map(int,input().split()))
tt=0
i=0
while(i<N):
    k1=-1
    j=0
    c=0
    while(j<K and i<N):
        if (A[i]!=0):
            k1=i
        c=c+A[i]
        i=i+1
        j=j+1
        
    while(c>=M and i<N):
        if (A[i]!=0):
            k1=i
        c=c+A[i]-A[i-K]
        i=i+1

    if (k1<0):
        tt=-1
        break

    elif (c<M and j==K):
        tt=tt+1
        i=k1+K
    #print(i,c)
    
print(tt)
        
    
    
