266B

#include <stdio.h>

#define MAXSIZE 1024

char que[MAXSIZE];

int main()
{
    int n, t;
    scanf("%d %d", &n, &t);
    scanf("%s", que);
    int i, j;
    char temp;
    for(j=1; j<=t; ++j)
    {
        for(i=0; i<n-1; ++i)
        {
            if((que[i]=='B')&&(que[i+1]=='G'))
            {
                //printf("%dseconds:%d %d\n", j, i, i+1);
                temp=que[i];
                que[i]=que[i+1];
                que[i+1]=temp;
                i+=1;
                //printf("The i is equal to %d.\n", i);
            }
        }
    }
    for(i=0; i<n; ++i)
        printf("%c", que[i]);
    printf("\n");
    return 0;
}