#include <stdio.h>
 
int main(void)
{
    int var_inp, var_dump = 0, res = 0;
 
    if (scanf("%d", &var_inp) !=1 || var_inp < 10) {
        printf("Input error");
        return 0;
    }
 
    while(var_inp > 10) {
 
		var_dump = var_inp / 10;
		int var_1 = var_dump * 10;
		res += var_inp - var_1;
		var_inp = var_dump;
        if (var_inp < 10) {
            res += var_inp;
        }
 
	}
 
	printf("%d", res);
 
    return 0;
}

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