#include <stdio.h>
#define maxn 1000010
int main()
{
	char ch;
	int i,max,b[maxn];
	i=0;
	for (int j=1;j<=maxn;j++) 
		b[j]=0;
	while (1){
		scanf("%c",&ch);
		if (ch!='G'&&ch!='R') break; 
		i++;
		if (ch=='G') b[i]=1;
		else if (ch=='R') b[i]=-1;
		b[i]+=b[i-1];
	}
	max=0;
	//for (int j=1;j<=i;j++) printf("%d ",b[j]);
	//printf("\n");
	for (int j=0;j<i;j++){
	   if (max>i-j) break;
	   for (int k=i;k>j;k--)
	   if (b[k]==b[j]&&k-j>max) {max=k-j;break;} 
	}
	printf("%d\n",max);
}

#include <stdio.h>
#include <string.h>
#define maxn 100010
int main()
{
	char ch;
	int n,max,b[maxn];
	char s[100010];
	for (int j=1;j<=maxn;j++) 
		b[j]=0;
	scanf("%s",s);
	n=strlen(s);
     for (int i=1;i<=n;i++){
		if (s[i-1]=='G') b[i]=1;
		else b[i]=-1;
		b[i]+=b[i-1];
	}
	max=0;
	//for (int j=1;j<=i;j++) printf("%d ",b[j]);
	//printf("\n");
	for (int j=0;j<n;j++){
	   if (max>n-j) break;
	   for (int k=n;k>j;k--)
	   if (b[k]==b[j]&&k-j>max) {max=k-j;break;} 
	}
	printf("%d\n",max);
}