puncte3

#include <cstdio>
#define M 1001

int main()
{
    long int n,i,j,k,xs[M],ys[M],xd[M],yd[M],x0,y0,x1,y1;
    long np=0;
    FILE *fi,*fo;
    for(i=0;i<M;++i)
    	xs[i]=ys[i]=M+1,xd[i]=yd[i]=-1;
    fi=fopen("puncte3.in","rt");
    fscanf(fi,"%d",&n);
    for(i=0;i<n;++i)
    {
         fscanf(fi,"%d %d",&j,&k);
         if(j<xs[k])
             xs[k]=j;
		if(j>xd[k])
            xd[k]=j;
		if(k<ys[j])
            ys[j]=k;
        if(k>yd[j])
            yd[j]=k;
    }
    i=0;
    while(xd[i]<0)
        i++;
    y0=i;
    i=M-1;
    while(xd[i]<0)
        i--;
    y1=i;
    i=0;
    while(yd[i]<0)
        i++;
    x0=i;
    i=M-1;
    while(yd[i]<0)
        i--;
    x1=i;
    fclose(fi);
    do
    {
        k=0;
        for(i=x0;i<=x1;++i)
            for(j=ys[i];j<=yd[i];++j)
        	{
            	if(i<xs[j])
                	xs[j]=i,k=1;
				if(i>xd[j])
                	xd[j]=i,k=1;
        }
        for(j=y0;j<=y1;++j)
            for(i=xs[j];i<=xd[j];++i)
        	{
            	if(j<ys[i])
                	ys[i]=j,k=1;
				if(j>yd[i])
                	yd[i]=j,k=1;
        	}
	} while(k);
    for(j=y0;j<=y1;++j)
        if(xd[j]>=0)
        	np+=(xd[j]-xs[j]+1);
    fo=fopen("puncte3.out","wt");
    fprintf(fo,"%ld\n",np);
    fclose(fo);
	return 0;
}