uses crt;
const nmax=20;
type matr=array[1..nmax,1..nmax] of integer;
function Sred(a:matr;n,m:byte):real;
var i,j:byte;
s:real;
begin
s:=0;
for i:=1 to n do
for j:=1 to m do
s:=s+a[i,j];
Sred:=s/(n*m);
end;
var a:matr;
m,n,i,j:byte;
begin
clrscr;
randomize;
repeat
write('Количество строк до ',nmax,' n=');
readln(n);
until n in [1..nmax];
repeat
write('Количество столбцов до ',nmax,' m=');
readln(m);
until m in [1..nmax];
writeln('Исходная матрица:');
for i:=1 to n do
begin
for j:=1 to m do
begin
a[i,j]:=random(50);
write(a[i,j]:4);
end;
writeln;
end;
writeln;
write('Среднее арифметическое элементов матрицы=',Sred(a,n,m):0:2);
readln
end.