can someone tell why the following code for coin combinations 1 question from cses problemset is getting time limit exceeded

#include <bits/stdc++.h>
#define int long long
using namespace std;
int MOD=1e9+7;
signed main()
{
    
    int n,x;
    cin>>n>>x;
    int nums[n];
    for(int i=0;i<n;i++){
        cin>>nums[i];
    }
    int dp[x+1]={0};
    dp[0]=1;
    for(int i=1;i<=x;i++){
        for(int q:nums){
            if(i-q>=0){
                dp[i]+=dp[i-q];
                dp[i]%=MOD;
            }
        }
    }
    cout<<dp[x]<<endl; 
}

I tried changing the variable MOD from int MOD to const int MOD and it worked. i don’t know what really changed in the code with it as i’m not changing the value of MOD anywhere.