#include <cstdio>
#include <cstring>
#include <ctime> 

#define file_in "zeap.in"
#define file_out "zeap.out"

#define Inf 0x3f3f3f3f

int nr,zeap[301000];
char s[100];

inline int abs(int a) { return a>=0?a:-a; }

void insert(int x)
{
	int ok=0,i;
	for (i=1;i<=nr && !ok;++i)
		 if (zeap[i]==x)
		      ok=1;
	
	if (!ok)
		zeap[++nr]=x;
}

int sterge(int x)
{
	int ok=0,poz,i;
	for (i=1;i<=nr && !ok;++i)
		 if (zeap[i]==x)
		      poz=i,
			  ok=1;
	
	if (!ok)
		return 1;
	else
	{
		for (i=poz;i<=nr;++i)
			 zeap[i]=zeap[i+1];
		nr--;
		return 0;
	}
}


int cauta(int x)
{
    int ok=0,i;
	for (i=1;i<=nr && !ok;++i)
		 if (zeap[i]==x)
		      ok=1;
	
	return ok;
}
	
int max_dif()
{
	int max=0,i,j;
	
	for (i=1;i<nr;++i)
		 for (j=i+1;j<=nr;++j)
			  if (abs(zeap[i]-zeap[j])>max)
				  max=abs(zeap[i]-zeap[j]);
	
	return max;
}	

int min_dif()
{
	int min=Inf,i,j;
	
	for (i=1;i<nr;++i)
		 for (j=i+1;j<=nr;++j)
			  if (abs(zeap[i]-zeap[j])<min)
				  min=abs(zeap[i]-zeap[j]);
	
	return min;
}	

	
int main()
{
	int i,x;
	freopen(file_in,"r",stdin);
	freopen(file_out,"w",stdout);
	
	memset(zeap,0,sizeof(zeap));
	nr=0;
	
	while(gets(s))
	{
		//gets(s);
		i=0;
		if (s[0]=='I')//insert
		{
			i=2;
			x=0;
			while(s[i]>='0' && s[i]<='9')
			{
				x=x*10+s[i]-'0';
				i++;
			}
			insert(x);
		}
		else
		if (s[0]=='S')//sterge
		{
			i=2;
			x=0;
			while(s[i]>='0' && s[i]<='9')
			{
				x=x*10+s[i]-'0';
				i++;
			}
			if (sterge(x))
				printf("-1\n");
			
		}
		else	
		if (s[0]=='C')//cauta
		{
			i=2;
			x=0;
			while(s[i]>='0' && s[i]<='9')
			{
				x=x*10+s[i]-'0';
				i++;
			}
			printf("%d\n", cauta(x));			
		}
		else
		if (s[0]=='M' && s[1]=='A')//max
		{
			if (nr<2)
				printf("-1\n");
			else
				printf("%d\n", max_dif());
		}
		else
		if (s[0]=='M' && s[1]=='I')//min 
        { 
			if (nr<2)
				printf("-1\n");
			else
				printf("%d\n", min_dif());
		}	
    }

	fclose(stdin);
	fclose(stdout);
	
	return 0;
}