#include<bits/stdc++.h>
using namespace std;
#define rep(i,N) for(int (i)=0;(i) < (N); (i)++)
#define all(V) V.begin(), V.end()
using i64 = int_fast64_t;
using P = pair<i64,i64>;

int main(){
    int N;
    cin >> N;
    i64 out = 0;
    i64 a,b;
    rep(i,N){
        cin >> a >> b;
        out += b;
    }

    cout << out + 1 << endl;
}