func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     int x = 0, f = 1;     char ch = getchar();     while (ch <  0  || ch >  9 ) {       f = ch ==  -  ? -1 : 1;       ch = getchar();     }     while (ch >=  0  && ch <=  9 ) x = x * 10 + ch -  0 , ch = getchar();     return x * f;   }   const int N = 105;   int n, p[N], c[N];   int main() {     int T = read();     while (T--) {       n = read();       for (int i = 1; i <= n; i++) p[i] = read(), c[i] = read();       p[0] = 0;       c[0] = 0;       int fl = 1;       for (int i = 1; i <= n; i++) {         if (c[i] < c[i - 1] || p[i] < p[i - 1]) {           fl = 0;           break;         }         if (c[i] - c[i - 1] > p[i] - p[i - 1]) {           fl = 0;           break;         }       }       if (fl)         puts( YES );       else         puts( NO );     }   }   