#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int main() {

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    char ch;
    int level = 0;
    int valleyCount = 0;
    
    for (ch = getchar(); ch != EOF; ch = getchar()){
        if (ch == 'U'){
            if (level == -1){
                valleyCount++;
            }
            level++;
        } else if (ch == 'D'){
            level--;
        }
    }
    
    if (level < 0){
        valleyCount++;
    }
    
    printf("%d\n", valleyCount);
    return 0;
}