/* Counts only the numeric characters '0' - '9'
   read from standard input */

#include <stdio.h>
int main( void )
{
    int c, n = 0;

    while ( ( c = getchar() ) != '\n' ) {
        if ( c >= '0' && c <= '9' )
            n = n + 1;
    }
    printf( "Count of digits = %d\n", n );
}