from copy import copy

N=int(input())
Y=[0]+list(map(int,input().split()))+[10**10]
Z=copy(Y)

for i in range(N):
    if Y[i]<=Y[i+1] and Y[i+1]>Y[i+2]:
        if Y[i]<=Y[i+2]:
            Y[i+1]=Y[i+2]
        else:
            Y[i+1]=Y[i]
            Y[i+2]=Y[i]

C=0
for j in range(1,N+1):
    C+=abs(Z[j]-Y[j])
print(C)