第三个点WA求助QAQ

#include <iostream>
#include <map>
#include <algorithm>
using namespace std;
map<long long,int>M;
map<long long, int>::iterator it;
int main()
{
    long long N, C;
    cin >> N >> C;
    for (int i = 0; i < N; i++)
    {
        long long a;
        cin >> a;
        M[a]++;
    }
    int ans = 0;
    for (it = M.begin(); it != M.end(); it++)
    {
        if(M.find(it->first+C)!=M.end())
            ans += it->second*M[it->first + C];
    }
    cout << ans << endl;
    return 0;
}