#include <bits/stdc++.h>

using namespace std;

long long x,n,i,t;

int main()

{

cin>>n;

t=0;

for (i=1; i<=n; i++)

{

cin>>x;

if (x>0) t+=x;

}

cout<<t;

return 0;

}

Khi nãy gửi nhầm 2 cái nha 

program Baitap1;

uses crt;

var Min ,n, i:integer;

      A: array [1..1000] of integer;

begin

clrscr;

write('Nhap N ');readln(n);

for i:=1 to n do begin

   write('A[',i,']=');readln(A[i]);

                        end;

Min:=A[1];

for i:=1 to n do if Min>A[i] then Min:=A[i];

write('So Nho Nhat Trong Mang La ',Min);

readln;

end.       

uses crt;

var a:array[1..100]of integer;

i,n,dem:integer;

begin

clrscr;

repeat

write('Nhap n='); readln(n);

until (1<=n) and (n<=1000);

for i:=1 to n do 

  begin

write('A[',i,']='); readln(a[i]);

end;

writeln('Mang ban vua nhap la: ');

for i:=1 to n do 

  write(a[i]:4);

writeln;

dem:=0;

for i:=1 to n do 

  if a[i] mod 3=0 then inc(dem);

writeln('So phan tu chia het cho 3 la: ',dem);

readln;

end.

uses crt;

var a:array[1..100]of integer;

i,n,dem1,dem2:integer;

begin

clrscr;

readln(n);

for i:=1 to n do readln(a[i]);

for i:=1 to n do write(a[i]:4);

writeln;

dem1:=0;

for i:=1 to n do 

  if (a[i]>a[i-1]) and (a[i]>a[i+1]) then dem1:=dem1+1;

dem2:=0;

for i:=1 to n do 

  if (a[i]<a[i-1]) and (a[i]<a[i+1]) then dem2:=dem2+1;

writeln(dem1);

writeln(dem2);

readln;

end.

#include <bits/stdc++.h>

using namespace std;

long long a[1000],i,n,t;

int main()

{

cin>>n;

for (i=1; i<=n; i++) cin>>a[i];

for (i=1; i<=n; i++)

if (a[i]%3==0) t+=a[i];

cout<<t;

return 0;

}