#include <cstdio>

FILE *in = fopen("operatii.in","r"), *out = fopen("operatii.out","w");

int n;
int x, y;
long long cnt;

int main()
{
    fscanf(in, "%d", &n);

    fscanf(in, "%d", &x);

    cnt += x;

    for ( int i = 2; i <= n; ++i )
    {
        fscanf(in, "%d", &y);

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

        x = y;
    }

    fprintf(out, "%lld\n", cnt);


	return 0;
}