#include <cstdio>

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

    int i,N,now,prec;
    long long ans = 0;

    scanf("%d",&N);
    for(prec = 0, i = 1; i <= N; ++i)
    {
        scanf("%d",&now);
        if( now > prec ) ans += now - prec;
        prec = now;
    }

    printf("%lld\n", ans);



return 0;
}