#include <cstdio>
int main(){
	int V[4],X[3],T=0,R,i,j,r;
	for(i=0;i<4;i++)scanf("%d",&V[i]),T+=V[i];R=T;
	int bag[T+1];
	for(X[0]=1;X[0]<=30;X[0]++)for(X[1]=X[0]+1;X[1]<=30;X[1]++)for(X[2]=X[1]+1;X[2]<=30;X[2]++){
		for(j=0;j<=T;j++)bag[j]=!j;
		for(i=0;i<3;i++)for(int j=X[i];j<=T;j++)if(bag[j-X[i]]&&(!bag[j]||bag[j]>bag[j-X[i]]))bag[j]=bag[j-X[i]]+1;
		for(i=r=0;i<4;r+=bag[V[i++]]-1)if(!bag[V[i]])break;
		if(i==4&&R>r)R=r;
	}
	printf("%d\n",R);
}