C :

#include<stdio.h>
int main(){
  int n1, n2, n3;
  scanf("%d%d%d", &n1, &n2, &n3);
  if(n1 + n2 > n3 && n1 + n3 > n2 && n2 + n3 > n1){
    printf("YES");
  } else {
    printf("NO");
  }
  return 0;
}

C++ :

#include<stdio.h>   
int main()
{ 
	int a,b,c;
	scanf("%d%d%d",&a,&b,&c);
if ((a + b > c) && (a - b < c))	
	printf("YES");
else 
    printf("NO");

	return 0;
}

Pascal :

program ex20150108;
var
 a,b,c:integer;
begin
 readln(a,b,c);
 if (a+b>c) and (a+c>b) and (b+c>a) then
  write ('YES')
 else
  write('NO');
end.