#include <iostream>

using namespace std;

int main(){
    int n(0),m(0),last(0),temp_f(0),temp_s(0),end_(0);
    cin >> n >> m;
    for(int i = 0;i<n;++i){
        cin >> temp_f >> temp_s;
        last += temp_f-2-temp_s;
    }
    end_ = last + (m - 2);
    if(end_ < 0)cout << "Big Bang!";
    else cout << end_;

    return 0;
}