View Code of Problem 67

#include <stdio.h>

int main() {
    int x1, x2, y1, y2, x3, x4, y3, y4;
    while(~scanf("%d%d%d%d", &x1, &y1, &x2,&y2)){
        getchar();
        scanf("%d%d%d%d", &x3, &y3, &x4,&y4);
        int k1 = (y2-y1) / (x2 - x1);
        int k2 = (y4-y3) / (x4 - x3);
        if(k1 != k2)
            printf("Yes\n");
        else
            printf("No\n");
    }
    return 0;
}