1 #include<stdio.h>
 2 int main ()
 3 {
 4     long long a,b,s;
 5     
 6     while(scanf("%lld%lld",&a,&b)==2)
 7     {
 8         s=a-b;
 9         printf("%lld\n",s);
10     }
11     
12     return 0;
13 }