#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int N;

int main() {

    FILE *fin = fopen("sunny.in", "r");
    FILE *fout = fopen("sunny.out", "w");
    int h1, m1, h2, m2, t, m, i;
    double h, res = 0;
    char ampm1[3], ampm2[3];

    fscanf(fin, "%d", &N);

    for (i = 0; i < N; i++) {

        fscanf(fin, "%02d:%02d %s %02d:%02d %s %d",
            &h1, &m1, &ampm1[0], &h2, &m2, &ampm2[0], &t);

        if (ampm1[0] == ampm2[0]) {

            if (h1 ==12 && m1 == 0 && h2 == 12 && m2 == 0) {

                m = 24*60;

            } else {

                if (h1 == 12 && m1 == 0) {
                    h1 = 0;
                } else if (h2 == 12 && m2 == 0) {
                    h2 = 24;
                }

                m = (h2*60+m2)-(h1*60+m1);
            }

        } else {

            if (h1 ==12 && m1 == 0 && h2 == 12 && m2 == 0) {

                m = 12*60;

            } else {

                if (h1 == 12 && m1 == 0) {
                    h1 = 0;
                } else if (h2 == 12 && m2 == 0) {
                    h2 = 0;
                }

                h2 += 12;

                m = (h2*60+m2)-(h1*60+m1);
            }
        }

        h = (double)m / (double)60;
        res = res + h*(double)t*sqrt((double)t);
    }

    fprintf(fout, "%.3lf\n", res);

    return 0;
}