C - Typical Stairs

#include <iostream>

using namespace std;

int frv[100001],dp[100001];

int main()
{
    int n,m,i,j,a,stop;
    cin>>n>>m;
    for(i=0;i<m;i++){
        cin>>a;
        frv[a]=1;
    }
    dp[0]=1;
    for(i=1;i<=n;i++){
        stop=min(i,2);
        for(j=1;j<=stop;j++){
            if(frv[i-j]!=1){
                dp[i]=(dp[i]+dp[i-j])% 1000000007;
            }
        }
    }
    cout<<dp[n];
    return 0;
}