CF1060D

#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define ll long long

template<typename T>
inline void read(T&x){
    x=0;T k=1;char gc;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c)){x=x*10+c-'0';gc;}x*=k;
}

const int N=1e5+7;

int L[N];
int R[N];

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int n;r(n);
    for(int i=0;i<n;++i){
        r(L[i]),r(R[i]);
    }
    sort(L,L+n);
    sort(R,R+n);
    ll ans=n;
    for(int i=0;i<n;++i){
        ans+=max(L[i],R[i]);
    }
    printf("%lld\n",ans);
    return 0;
}