#27539: _CPP
#include <iostream>
using namespace std;
int main(){
long long a, b;
while (cin >> a >> b){
cout << abs(a-b) <<endl;
}
}
#include <iostream>
using namespace std;
int main(){
long long a, b;
while (cin >> a >> b){
cout << abs(a-b) <<endl;
}
}