Maximum Submatrix Sum

#include<stdio.h>
typedef long long int ll;
ll max(ll a,ll b){
    return (a > b ? a : b);
}

int main()
{
    int n;
    int h,m;

    scanf("%d %d %d",&n,&h,&m);
    ll x;
    ll a[n+1];a[0] = 0;
    ll sa = 0;
    ll maxa = 0;

    ll b[n+1];b[0] = 0;
    ll sb = 0;
    ll maxb = 0;
    for(int i=1;i<=n;i++){
        scanf("%lld",&a[i]);
        sa += a[i];
        if(i >= h){
            sa -= a[i-h];
            maxa = max(maxa,sa);
        }
    }
    for(int i=1;i<=n;i++){
        scanf("%lld",&b[i]);
        sb += b[i];
        if(i >= m){
            sb -= b[i-m];
            maxb = max(maxb,sb);
        }
    }
//  printf("Test %lld %lld\n",maxa,maxb);
    printf("%lld",maxa*m + maxb*h);
    return 0;
}