Description
The children are playing a matching game. There are \(n\) boys and \(m\) girls, numbered \(1 \sim n\) and \(1 \sim m\) respectively. If the sum of the numbers of boy \(i\) and girl \(j\) is a multiple of 5, they are called a reasonable one pair. Program a reasonable total number of pairs.
Format
Input
The first line is a positive integer \(t(≤100)\), which represents the number of data sets;
the next \(t\) line, each line contains two positive integers \(n\) and \(m\) (\(1≤n, m ≤10^8\)), which represent the number of boys and girls, respectively.
Output
For each set of data, output a reasonable total number of pairs.
Sample
Input
2
6 12
21 21
Output
14
88
Sample Code
#include <cstdio>
typedef long long ll;
int main(){
freopen("pairs.in", "r", stdin);
freopen("pairs.out", "w", stdout);
int t, n, m;
scanf("%d", &t);
while (t--){
scanf("%d %d", &n, &m);
/*ll ans=0;
for (int i=1; i<=n; i++)
ans+=m/5+((m%5+i%5)>=5);
//ans+=(i+m)/5-i/5;
cout<<ans<<endl;*/
ll x=n/5, y=m/5;
int u=n%5, v=m%5;
ll ans=x*y*5+u*y+v*x+((u+v)>4?u+v-4:0);
printf("%lld\n", ans);
}
return 0;
}