#include <bits/stdc++.h>
using namespace std;
int cnt_mod(long long l, long long r, int rem) {
if (l > r) return 0;
long long first = l;
while (first <= r && first % 5 != rem) first++;
if (first > r) return 0;
return (r - first) / 5 + 1;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
long long dp[5] = {};
dp[0] = 1;
for (int i = 1; i <= n; i++) {
int v, w;
cin >> v >> w;
long long cnt[5] = {};
for (int r = 0; r < 5; r++) {
cnt[r] = cnt_mod(v, w, r);
}
long long ndp[5] = {};
for (int a = 0; a < 5; a++) {
for (int b = 0; b < 5; b++) {
ndp[(a + b) % 5] += dp[a] * cnt[b];
}
}
for (int j = 0; j < 5; j++) dp[j] = ndp[j];
}
int val[5] = {1, 4, 5, 5, 4};
long long ans = 0;
for (int r = 0; r < 5; r++) {
ans += dp[r] * val[r];
}
cout << ans << '\n';
return 0;
}
