> #include <stdio.h>
> #include <stdlib.h>
> 
> int main()
> {
> 	int i = 0,j,n,max,min,num=0,nb[150000];
> 	scanf("%d",&n);
> 	for(j = 0; j < n; j++)
> 	{
> 		scanf("%d",&nb[j]);
> 	}
> 	while(i < n-1)
> 	{
> 		max = nb[i];
> 		while(max < nb[++i])
> 		{
> 			max = nb[i];
> 			if(i == n-1) break;
> 		}
> 		num += max;
> 		if(i == n-1)
> 		{
> 			printf("%d\n",num);
> 			return 0;
> 		}
> 		min = nb[i];
> 		while(min > nb[++i])
> 		{
> 			min = nb[i];
> 			if(i == n-1)
> 			{
> 				min = 0;break;
> 			}
> 
> 		}
> 		num -= min;
> 		if(i == n-1)
> 		{
> 			printf("%d\n",num);
> 			return 0;
> 		}
> 	}
> 	return 0;
> }