#include <cstdio>

using namespace std;

int main()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);

    int n,last=0,x,i;
    long long cnt=0;

    scanf("%d",&n);

    for(i=1;i<=n;i++)
    {
        scanf("%d",&x);

        if(x>last) cnt+=x-last;

        last=x;
    }

    printf("%lld",cnt);

    return 0;
}