#include<bits/stdc++.h>

using namespace std;

int main() {
    int n, b;
    double a, sum = 0;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a >> b;
        sum += a * b;
    }
    sum = sum / 100 * 85 - 0.049;
    printf("%.1lf", sum);
    return 0;
}

#include<bits/stdc++.h>

using namespace std;

int main() {
    int n, b;
    double a, sum = 0;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a >> b;
        sum += a * b;
    }
    sum = sum / 100 * 85;
    printf("%.1lf", sum);
    return 0;
}

加上-0.049就AC，否则70分