typedef double M;
int JP(int n, M m[n][n]){
  int j, k;
  for(j=0; j<n-2; ++j) for(k=j+2; k<n; ++k) if(m[j][k] != 0) return 0;
  for(j=1; j<n; ++j) for(k=0; k<j; ++k) if(m[j][k] != 0) return 0;
  for(j=0; j<n-1; ++j) if(m[j][j+1] != 0) {
     if(m[j][j+1] != 1) return 0;
     else if (m[j][j] != m[j+1][j+1]) return 0;}
  return 1;}

#include <stdio.h>
int main(){
printf("%d\n", JP(2, (M[2][2]){{1, 0}, {0, 1}}));
printf("%d\n", JP(3, (M[3][3]){{2, 1, 0}, {0, 2, 0}, {0, 0, 3}}));
printf("%d\n", JP(3, (M[3][3]){{2, 1, 0}, {0, 2.1, 0}, {0, 0, 3}}));
printf("%d\n", JP(3, (M[3][3]){{0, 0, 0}, {0, 0, 0}, {0, 0, 0}}));

return 0;}