function surfaceArea(A) {
    let besides = [[1,0],[-1,0],[0,1],[0,-1]]
    let surface = 0
    for(let i=0; i<A.length; i++){
        for(let j=0; j<A[0].length; j++){
            surface += 2
            for(let [r,h] of besides){
               surface += Math.max(A[i][j] - (A[i+r]?.[j+h] || 0), 0);
            }
        }
    }
    return surface
}