import std;

void main() {
    int n; scan(n);
    int ans = 1;
    foreach (_; 0..n-1) {
        int a, b; scan(a, b);
        ans += b;
    }
    writeln(ans);
}

void scan(T...)(ref T a) {
    string[] ss = readln.split;
    foreach (i, t; T) a[i] = ss[i].to!t;
}
T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;