Tacografo.c

#include <stdio.h>

int main() {
    int n, i;
    scanf("%d", &n);

    int dist_total = 0;

    for(i = 0; i < n; i++) {
        int T, V;
        scanf("%d %d", &T, &V);

        dist_total += V * T;
    }

    printf("%d\n", dist_total);

    return 0;
}