#include <stdio.h>
#include <unistd.h>

int mem[] = {0, 0, 0};
int sum() {
    return mem[0] + mem[1] + mem[2];
}

int main(void) {
    int count = 0;
    int curr;
    int prev = 0;
    int i = 0;
    while(scanf("%d\n", &curr) != EOF) {
        mem[i++ % 3] = curr;
        if (i > 3) {
            if (prev && sum() > prev) {
                count++;
            }
            prev = sum();
        }
        i++;
    }
    printf("%d\n", count);
    return 0;
}