\(AC\kern 0.4em CODE:\)

#include<bits/stdc++.h>

#define ri register int

#define p(i) ++i

using namespace std;

namespace IO{

    char buf[1<<21],*p1=buf,*p2=buf;

    #define gc() p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++

    inline int read() {

        ri x=0,f=1;char ch=gc();

        while(ch<'0'||ch>'9') {if (ch=='-') f=-1;ch=gc();}

        while(ch>='0'&&ch<='9') {x=(x<<1)+(x<<3)+(ch^48);ch=gc();}

        return x*f;

    }

}

using IO::read;

namespace nanfeng{

    #define int long long

    #define cmax(x,y) ((x)>(y)?(x):(y))

    #define cmin(x,y) ((x)>(y)?(y):(x))

    #define FI FILE *IN

    #define FO FILE *OUT

    #undef bool

    static const int N=1e5+7;

    struct Matrix{

        int x1,y1,x2,y2;

        friend inline bool operator<(Matrix m1,Matrix m2) {return m1.x1<m2.x1;}

        Matrix(){}

        Matrix(int x1,int y1,int x2,int y2):x1(x1),y1(y1),x2(x2),y2(y2){}

    }mat[N];

    int n,ans;

    inline int calc(Matrix m) {

        int res=0;

        int x=m.x2-m.x1,y=m.y2-m.y1;

        if (x>y) swap(x,y);

        res+=(x*x<<1);

        res+=(y-x)*(x<<1);

        return res;

    }

    inline int main() {

        // FI=freopen("nanfeng.in","r",stdin);

        // FO=freopen("nanfeng.out","w",stdout);

        n=read();

        for (ri i(1);i<=n;p(i)) {

            int x1=read(),y1=read(),x2=read(),y2=read();

            mat[i]=Matrix(x1,y1,x2,y2);

        }

        if (n==1) {printf("%lld\n",calc(mat[1]));return 0;}

        sort(mat+1,mat+n+1);

        // for (ri i(1);i<=n;p(i))

        for (ri i(1);i<n;p(i)) {

            ans+=calc(mat[i]);

            // printf("%lld %lld %lld %lld\n",mat[i].x1,mat[i].y1,mat[i].x2,mat[i].y2);

            for (ri j(i+1);j<=n;p(j)) {

                if (mat[j].x1-mat[i].x2>1) break;

                if (mat[j].x1-mat[i].x2==1) {

                    if (mat[j].y1-mat[i].y2>1||mat[i].y1-mat[j].y2>1) continue;

                    if (mat[j].y1-mat[i].y2==1||mat[i].y1-mat[j].y2==1) {ans+=1;continue;}

                    ans+=(cmin(mat[i].y2,mat[j].y2)-cmax(mat[i].y1,mat[j].y1))<<1;

                    if (cmax(mat[i].y2,mat[j].y2)>cmin(mat[i].y2,mat[j].y2)) ans+=1;

                    if (cmax(mat[i].y1,mat[j].y1)>cmin(mat[i].y1,mat[j].y1)) ans+=1;

                } else if (mat[j].y1>mat[i].y2) {

                    if (mat[j].y1-mat[i].y2>1) continue;

                    ans+=(cmin(mat[i].x2,mat[j].x2)-mat[j].x1)<<1;

                    if (mat[i].x1<mat[j].x1) ans+=1;

                    if (cmax(mat[i].x2,mat[j].x2)>cmin(mat[i].x2,mat[j].x2)) ans+=1;

                } else {

                    if (mat[i].y1-mat[j].y2>1) continue;

                    ans+=(cmin(mat[i].x2,mat[j].x2)-mat[j].x1)<<1;

                    if (mat[i].x1<mat[j].x1) ans+=1;

                    if (cmax(mat[i].x2,mat[j].x2)>cmin(mat[i].x2,mat[j].x2)) ans+=1;

                }

                // if (i==2) printf("%lld %lld %lld %lld ans=%lld\n",mat[j].x1,mat[j].y1,mat[j].x2,mat[j].y2,ans);

            }

            // printf("ans=%lld\n",ans);

        }

        // printf("%lld %lld %lld %lld\n",mat[n].x1,mat[n].y1,mat[n].x2,mat[n].y2);

        printf("%lld\n",ans+calc(mat[n]));

        return 0;

    }

    #undef int

}

int main() {return nanfeng::main();}