#include <stdio.h>

long long n,i,last,curent,sol;

int main(){
    freopen ("operatii.in","r",stdin);
    freopen ("operatii.out","w",stdout);
    
    scanf("%lld",&n);
    last=0;
    for (i=1;i<=n;i++){
        scanf("%lld",&curent);
        if (last<curent)sol+=(long long)curent-last;
        last=curent;
    }
    
    printf("%lld\n",sol);
    
    return 0;
}