#includestdio.h #includeconio.h main() {int i=0,m=0,k,j,n=0,l,first; int x[3]={1,25,50},y=1; int day(int); int a[2][13]={{31,28,31,30,31,30,31,31,30,31,30,31}, {31,29,31,30,31,30,31,31,30,31,30,31}}; printf("please input the year:"); scanf("%d",&a...