inps=list(map(int,input().split(',')))
ans=[]
finish=[]
for i in range(len(inps)):
    if i not in finish:
        is_find=False
        for j in range(i+1,len(inps)):
            if inps[j]>=inps[i]:
                ans.append([i,j,min(inps[i],inps[j])])
                finish.extend([k for k in range(i+1,j)])
                is_find=True
                break
        if not is_find and i!=len(inps)-1:
            finish.append(i)
            ans.append([i,i+1,min(inps[i],inps[i+1])])
sum=0
for i in ans:
    sum +=(i[1]-i[0])*i[2]
print(sum)

create table t_numbers(number int, frequency int);
insert into  t_numbers(number,frequency) values(1,1);
insert into  t_numbers(number,frequency) values(2,3);
insert into  t_numbers(number,frequency) values(4,4);