def main():
    inp1 = int(input())
    inp2 = list(map(int, input().split()))
    
    
    ans = 0
    for v in range(1, inp1 + 1):
        vcoo = v - 1 
        for s in range(1, inp1 + 1):
            scoo = s - 1
            
            once = abs(v - s) * abs(inp2[vcoo] - inp2[scoo])
            ans = ans + once

    print(ans)            
    
        


if __name__ == '__main__':
    main()