AAAAAAAAAAAAAAaaaaaaaaaEEEEEEEaaaaaaaaaaaa Source

#include <stdio.h>
#define E else if
int main(){int c,d,i,e=0;char b[1000],a[26]={0};gets(b);for(i=0;b[i]>0;++i){c=b[i];d=b[i
+1];if(e){if(c>93){--e;++i;continue;}if(d==0)b[i]=-1;}if(c
>96)a[c-97]--;E(c>95)a[d-65]=getchar();E(c> 
94)putchar(a[d-65]);E(c>93&&a[d-65]==0)e=1;E(c>64)a[c-65]++;}}