#include <cstdio>
#define MAXN 1000000
int v[MAXN+1];
int main(){
    FILE*fi,*fout;
    int i,n;
    long long con;
    fi=fopen("operatii.in" ,"r");
    fout=fopen("operatii.out" ,"w");
    fscanf(fi,"%d" ,&n);
    for(i=1;i<=n;i++)
       fscanf(fi,"%d" ,&v[i]);
    con=0;
    for(i=0;i<n;i++)
       if(v[i]<v[i+1])
          con=con+v[i+1]-v[i];
    fprintf(fout,"%lld" ,con);
    fclose(fi);
    fclose(fout);
    return 0;
}