CF1190A代码求助

#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
long long f[100001],ans,n,k,i,j,m;
int main()
{
	scanf("%d%d%d",&n,&m,&k);
	for(i=1;i<=m;i++)
	{
		scanf("%d",&f[i]);
	}
	i=1;
	for(i=1;i<=m;i++)
	{
		long long x=f[i]%k,sum=1;
		f[i]=f[i]/k*k;
		if(x)f[i]+=k;
		for(j=i+1;f[j]<=f[i]&&j<=m;j++)
		{
			sum++;
		}
		i+=sum-1;
		for(j=i;j<=m;j++)
		{
			f[j]-=sum;
		}
		ans++;
	}
	printf("%d",ans);
	return 0;
}

泥古uke，CF第十组WA，输出是1，标答是99991