#include <stdio.h>

#include <stdlib.h>

/* run this program using the console pauser or add your own getch, system("pause") or input loop */

int main(int argc, char *argv[]) {

int a,b,c,d;

scanf("%d %d %d %d",&a,&b,&c,&d);

if(b-a==d-c){

printf("%d %d %d %d %d",a,b,c,d,d+(d-c));

}else if(d/c==c/b){

        printf("%d %d %d %d %d",a,b,c,d,d*(d/c));

}

return 0;

}

你的t呢?