#include <bits/stdc++.h>

using namespace std;

string st;

int d,i,dem;

int main()

{

freopen("xau.inp","r",stdin);

freopen("xau.out","w",stdout);

cin>>st;

d=st.length();

dem=0;

for (i=0; i<=d-1; i++)

if (st[i]=='a') dem++;

cout<<dem;

return 0;

}

Bài 1:

Program HOC24;

const fi='in.txt';

fo='out.txt';

var f: text;

i,n: integer;

t: longint;

procedure ip;

begin 

assign(f,fi);

reset(f);

read(f,n);

close(f);

end;

procedure out;

begin

assign(f,fo);

rewrite(f);

t:=1;

for i:=1 to n do t:=t*i;

write(f,t);

close(f);

end;

begin

ip;

out;

end.

Bài 2:

Program HOC24;

const fi='in.txt';

fo='out.txt';

var f: text;

i: byte;

a: array[1..4] of string;

procedure ip;

begin 

assign(f,fi);

reset(f);

for i:=1 to 4 do readln(f,a[i]);

close(f);

end;

procedure out;

begin

assign(f,fo);

rewrite(f);

for i:=1 to 4 do writeln(f,a[i]);

close(f);

end;

begin

ip;

out;

end.

1: 

const fi='inp.txt';

fo='out.txt';

var n,i:integer;

s:real;

begin

assign(f1,fi); reset(f1);

assign(f2,fo); rewrite(f2);

readln(f1,n);

s:=1;

for i:=1 to n do 

  s:=s*i;

writeln(f2,s:4:2);

close(f1);

close(f2);

end.

#include <bits/stdc++.h>
using namespace std;
unsigned long long a[1000],i,n,uc;
//chuongtrinhcon
unsigned long long ucln(long long a,long long b)
{
    if (b==0) return(a);
    else return(ucln(b,a%b));
}
//chuongtrinhchinh
int main()
{
    freopen("sn3.inp","r",stdin);
    freopen("uc.out","w",stdout);
    cin>>n;

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

uc=ucln(a[1],a[2]);

for (i=3; i<=n; i++)

uc=ucln(uc,a[i]);

cout<<uc;
    return 0;
}

nhờ viết thành pascal hộ nhé

const fi='mang.txt';

fo='tong.txt';

var f1,f2:text;

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

n,i,t:integer;

begin

assign(f1,fi); reset(f1);

assign(f2,fo); rewriteln(f2);

n:=0;

while not eof(f1) do 

  begin

inc(n);

read(f1,a[n]);

end;

t:=0;

for i:=1 to n do 

  t:=t+a[i];

writeln(f2,t);

close(f1);

close(f2);

end.