#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
char str[1000000];
int i=0,counter=0,point=0;
scanf("%s",&str);
while(str[i++]!='\0')
{
counter++;
}
i=0;
while(i<counter)
{
if( (i+1) == counter )
{
break;
}
else
{
if(str[i]==str[i+1] || str[i] == '?' || str[i+1] == '?')
{
point++;
i+=2;
}
else
{
i+=1;
}
}
}
printf("%d",point);
return 0;
}