Peça-[OBI]

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

int main() {

    int number, quant, i, certo, j, igual = 0;

    scanf("%d", &quant);

    int numbers[quant-1];

        for(i=0; i<quant-1; i++) {

            scanf("%d", &numbers[i]);
        }

        for(i=1; i<=quant; i++) {

            for(j=0; j<quant-1; j++) {

                if(i == numbers[j]) {

                    igual = 1;
                    break;
                }

                else {

                    certo = i;
                    continue ;

                }
            }

        if(igual == 0)  {

            printf("%d", certo);
            break;
        }

        else  { igual = 0; }
            }

        return 0;
}