Destruction

#include<stdio.h>
typedef long long int ll;
ll const inf = 1e18;

ll max(ll a,ll b){
    return (a > b ? a : b);
}
int main()
{
    int n,K,m;
    scanf("%d %d %d",&n,&K,&m);
    ll arr[n+1];
    ll qs[n+1];qs[0] = 0;
    arr[0] = 0;
    for(int i = 1 ; i <= n ; i ++){
        scanf("%lld",&arr[i]);
        qs[i] = qs[i-1] + arr[i];
    }

    ll dp[n+1][2];
    for(int i = 0 ; i <= 1 ; i ++)dp[0][i] = -inf;
    for(int i = 0 ; i <= n ; i ++)dp[i][0] = qs[i];

    for(int k = 1 ; k <= K ; k ++){
        ll maxPrefix = -inf;
        if(k == 2)dp[0][k%2] = -inf;
        for(int I = 1 ; I <= n ; I ++){
            ll ans = dp[I-1][k%2] + arr[I];
        //  printf("skiped %lld : (%lld + %lld) = %lld\n",I,dp[I-1][k],arr[I],ans);
            if(I-m+1 >= 1){
                maxPrefix = max(maxPrefix,((I-m+1)-2 >= 0 ? dp[(I-m+1)-2][(k+1)%2] : dp[0][(k+1)%2]) + arr[I-m]);//dp[(I-m+1)-2])
            }
        //  printf("Test (%lld,%lld) : ans = max(%lld,%lld)\n",maxPrefix,ans);
            ans = max(maxPrefix,ans);
        //  printf("Test (%lld,%lld) : %lld\n",I,k,ans);
            dp[I][k%2] = ans;
        //  printf("%lld ",dp[I][k%2]);
        }
    //  printf("\n");
    }
    printf("%lld",dp[n][K%2]);
    return 0;
}