POJ 1006

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
int r=3;
int m[4]={0,23,28,33};
int a[4]={0};

void exgcd(int a,int b,int &d,int &x,int &y){
	if(b==0){
		x=1; y=0; d=a;
	}
	else{
		exgcd(b,a%b,d,x,y);
		int tmp=x;
		x=y;
		y=tmp-(a/b)*y;
	}
}

int China(int lim){
	int M=1;
	int i,Mi,x,y,d,ans=0;
	for(i=1;i<=r;i++)
	M*=m[i];
	for(i=1;i<=r;i++){
		Mi=M/m[i];
		exgcd(Mi,m[i],d,x,y);
		ans=(ans+Mi*x*a[i])%M;
	}
	while(ans<=lim)
	ans+=M;
	return ans;
}

int main(){
	int d,p,e,i; int kase=0;
	while(scanf("%d%d%d%d",&p,&e,&i,&d)!=EOF){
		if(p==-1&&d==-1&&e==-1&&i==-1) break;
		a[1]=p; a[2]=e; a[3]=i;
		int ans=China(d);
		printf("Case %d: the next triple peak occurs in %d days.\n",++kase,ans-d);
	}
	return 0;
}