C :

#include<stdio.h>

int main()
{
        int Y,M,D,m[13][2]={0,0,
                            31,31,
                            28,29,
                            31,31,
                            30,30,
                            31,31,
                            30,30,
                            31,31,
                            31,31,
                            30,30,
                            31,31,
                            30,30,
                            31,31};
        int i,k,d;
        while(scanf("%d%d%d",&Y,&M,&D)!=EOF)
        {
                k=0;
                if((Y%4==0&&Y%100!=0)||(Y%400==0))
                        k=1;
                for(d=0,i=1;i<M;i++)
                        d+=m[i][k];
                d+=D;
                printf("%d\n",d);
        }
        return 0;
}

C++ :

#include<stdio.h>

int main()
{
	int Y,M,D,m[13][2]={0,0,
						31,31,
						28,29,
						31,31,
						30,30,
						31,31,
						30,30,
						31,31,
						31,31,
						30,30,
						31,31,
						30,30,
						31,31};
	int i,k,d;
	while(scanf("%d%d%d",&Y,&M,&D)!=EOF)
	{
		k=0;
		if((Y%4==0&&Y%100!=0)||(Y%400==0))
			k=1;
		for(d=0,i=1;i<M;i++)
			d+=m[i][k];
		d+=D;
		printf("%d\n",d);
	}
	return 0;
}

Pascal :

program t;
const a:array[1..12]of integer=(31,28,31,30,31,30,31,31,30,31,30,31);
      b:array[1..12]of integer=(31,29,31,30,31,30,31,31,30,31,30,31);
var y,m,d,i,s:longint;
begin
 while not eof do
  begin
   read(y,m,d);
   s:=0;
   if (y mod 4=0)and(y mod 100<>0)or(y mod 400=0) then
    for i:=1 to m-1 do
     s:=s+b[i]
   else
    for i:=1 to m-1 do
     s:=s+a[i];
   writeln(s+d);
  end;
end.